Linux-kselftest-mirror

linux-kselftest-mirror@lists.linaro.org

135 participants
14278 discussions

Re: [PATCH] selftests/cgroup: conform test to TAP format output

by Michal Koutný

On Fri, Nov 14, 2025 at 11:55:48AM +0800, Guopeng Zhang <zhangguopeng(a)kylinos.cn> wrote: > Actually, selftests are no longer just something for developers to view locally; they are now extensively > run in CI and stable branch regression testing. Using a standardized layout means that general test runners > and CI systems can parse the cgroup test results without any special handling. Nice. I appreciate you took this up. > This patch is not part of a formal, tree-wide conversion series I am running; it is an incremental step to align the > cgroup C tests with the existing TAP usage. I started here because these tests already use ksft_test_result_*() and > only require minor changes to generate proper TAP output. The tests are in various state of usage, correctness and usefulness, hence... > > > I'm asking to better asses whether also the scripts listed in > > Makefile:TEST_PROGS should be converted too. > > I agree that having them produce TAP output would benefit tooling and CI. I did not want to mix > that into this change, but if you and other maintainers think this direction is reasonable, > I would be happy to follow up and convert the cgroup shell tests to TAP as well. ...I'd suggest next focus on test_cpuset_prs.sh (as discussed, it may need more changes to adapt its output too). Michal

1 month, 4 weeks

[PATCH bpf-next] selftests/bpf: simplify the kernel_count bench trigger

by Menglong Dong

Remove the "trigger_count" in trigger_bench.c and reuse trigger_driver() instead for trigger_kernel_count_setup(). With the calling to bpf_get_numa_node_id(), the result for "kernel_count" will become a little more accurate. It will also easier if we want to test the performance of livepatch, just hook the bpf_get_numa_node_id() and run the "kernel_count" bench trigger. Signed-off-by: Menglong Dong <dongml2(a)chinatelecom.cn> --- .../selftests/bpf/benchs/bench_trigger.c | 5 +---- .../testing/selftests/bpf/progs/trigger_bench.c | 17 +++++------------ 2 files changed, 6 insertions(+), 16 deletions(-) diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c index 1e2aff007c2a..34fd8fa3b803 100644 --- a/tools/testing/selftests/bpf/benchs/bench_trigger.c +++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c @@ -179,11 +179,8 @@ static void trigger_syscall_count_setup(void) static void trigger_kernel_count_setup(void) { setup_ctx(); - bpf_program__set_autoload(ctx.skel->progs.trigger_driver, false); - bpf_program__set_autoload(ctx.skel->progs.trigger_count, true); + ctx.skel->rodata->kernel_count = 1; load_ctx(); - /* override driver program */ - ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_count); } static void trigger_kprobe_setup(void) diff --git a/tools/testing/selftests/bpf/progs/trigger_bench.c b/tools/testing/selftests/bpf/progs/trigger_bench.c index 3d5f30c29ae3..6564d1909c7b 100644 --- a/tools/testing/selftests/bpf/progs/trigger_bench.c +++ b/tools/testing/selftests/bpf/progs/trigger_bench.c @@ -39,26 +39,19 @@ int bench_trigger_uprobe_multi(void *ctx) return 0; } +const volatile int kernel_count = 0; const volatile int batch_iters = 0; -SEC("?raw_tp") -int trigger_count(void *ctx) -{ - int i; - - for (i = 0; i < batch_iters; i++) - inc_counter(); - - return 0; -} - SEC("?raw_tp") int trigger_driver(void *ctx) { int i; - for (i = 0; i < batch_iters; i++) + for (i = 0; i < batch_iters; i++) { (void)bpf_get_numa_node_id(); /* attach point for benchmarking */ + if (kernel_count) + inc_counter(); + } return 0; } -- 2.51.2

1 month, 4 weeks

[PATCH net-next] selftests: drv-net: xdp: make the XDP qstats tests less flaky

by Jakub Kicinski

The XDP qstats tests send 2k packets over a single socket. Looks like when netdev CI is busy running those tests in QEMU occasionally flakes. The target doesn't get to run at all before all 2000 packets are sent. Lower the number of packets to 1000 and reopen the socket every 50 packets, to give RSS a chance to spread the packets to multiple queues. For the netdev CI testing either lowering the count or using multiple sockets is enough, but let's do both for extra resiliency. Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- CC: shuah(a)kernel.org CC: ast(a)kernel.org CC: hawk(a)kernel.org CC: john.fastabend(a)gmail.com CC: sdf(a)fomichev.me CC: linux-kselftest(a)vger.kernel.org --- tools/testing/selftests/drivers/net/xdp.py | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/drivers/net/xdp.py b/tools/testing/selftests/drivers/net/xdp.py index a148004e1c36..834a37ae7d0d 100755 --- a/tools/testing/selftests/drivers/net/xdp.py +++ b/tools/testing/selftests/drivers/net/xdp.py @@ -687,9 +687,12 @@ from lib.py import ip, bpftool, defer "/dev/null" # Listener runs on "remote" in case of XDP_TX rx_host = cfg.remote if act == XDPAction.TX else None - # We want to spew 2000 packets quickly, bash seems to do a good enough job - tx_udp = f"exec 5<>/dev/udp/{cfg.addr}/{port}; " \ - "for i in `seq 2000`; do echo a >&5; done; exec 5>&-" + # We want to spew 1000 packets quickly, bash seems to do a good enough job + # Each reopening of the socket gives us a differenot local port (for RSS) + tx_udp = "for _ in `seq 20`; do " \ + f"exec 5<>/dev/udp/{cfg.addr}/{port}; " \ + "for i in `seq 50`; do echo a >&5; done; " \ + "exec 5>&-; done" cfg.wait_hw_stats_settle() # Qstats have more clearly defined semantics than rtnetlink. @@ -704,11 +707,11 @@ from lib.py import ip, bpftool, defer cfg.wait_hw_stats_settle() after = cfg.netnl.qstats_get({"ifindex": cfg.ifindex}, dump=True)[0] - ksft_ge(after['rx-packets'] - before['rx-packets'], 2000) + expected_pkts = 1000 + ksft_ge(after['rx-packets'] - before['rx-packets'], expected_pkts) if act == XDPAction.TX: - ksft_ge(after['tx-packets'] - before['tx-packets'], 2000) + ksft_ge(after['tx-packets'] - before['tx-packets'], expected_pkts) - expected_pkts = 2000 stats = _get_stats(prog_info["maps"]["map_xdp_stats"]) ksft_eq(stats[XDPStats.RX.value], expected_pkts, "XDP RX stats mismatch") if act == XDPAction.TX: -- 2.51.1

1 month, 4 weeks

[PATCH net-next] selftests: drv-net: xdp: Fix register spill error with clang 20

by Dimitri Daskalakis

On clang 20.1.8 the XDP program fails to load with a register spill error. Since hdr_len is a __u32, the compiler decided it only needed the lower 32-bits of ctx->data, which later triggers the register spill verifier error. Suggested-by: Martin KaFai Lau <martin.lau(a)kernel.org> Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1(a)gmail.com> Signed-off-by: Jakub Kicinski <kuba(a)kernel.org> --- libbpf: prog 'xdp_prog': BPF program load failed: Permission denied libbpf: prog 'xdp_prog': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; return xdp_prog_common(ctx); @ xdp_native.bpf.c:670 0: (85) call pc+1 caller: R10=fp0 callee: frame1: R1=ctx() R10=fp0 2: frame1: R1=ctx() R10=fp0 ; static int xdp_prog_common(struct xdp_md *ctx) @ xdp_native.bpf.c:635 2: (bf) r7 = r1 ; frame1: R1=ctx() R7_w=ctx() 3: (b4) w1 = 0 ; frame1: R1_w=0 ; key = XDP_MODE; @ xdp_native.bpf.c:640 4: (63) *(u32 *)(r10 -336) = r1 ; frame1: R1_w=0 R10=fp0 fp-336=????0 5: (bf) r2 = r10 ; frame1: R2_w=fp0 R10=fp0 6: (07) r2 += -336 ; frame1: R2_w=fp-336 ; mode = bpf_map_lookup_elem(&map_xdp_setup, &key); @ xdp_native.bpf.c:641 7: (18) r1 = 0xff110001099ada00 ; frame1: R1_w=map_ptr(map=map_xdp_setup,ks=4,vs=4) 9: (85) call bpf_map_lookup_elem#1 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) 10: (bf) r8 = r0 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) R8_w=map_value(map=map_xdp_setup,ks=4,vs=4) 11: (b4) w6 = 2 ; frame1: R6_w=2 ; if (!mode) @ xdp_native.bpf.c:642 12: (15) if r8 == 0x0 goto pc+669 ; frame1: R8_w=map_value(map=map_xdp_setup,ks=4,vs=4) 13: (b4) w1 = 1 ; frame1: R1_w=1 ; key = XDP_PORT; @ xdp_native.bpf.c:645 14: (63) *(u32 *)(r10 -336) = r1 ; frame1: R1_w=1 R10=fp0 fp-336=????1 15: (bf) r2 = r10 ; frame1: R2_w=fp0 R10=fp0 16: (07) r2 += -336 ; frame1: R2_w=fp-336 ; port = bpf_map_lookup_elem(&map_xdp_setup, &key); @ xdp_native.bpf.c:646 17: (18) r1 = 0xff110001099ada00 ; frame1: R1_w=map_ptr(map=map_xdp_setup,ks=4,vs=4) 19: (85) call bpf_map_lookup_elem#1 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) ; if (!port) @ xdp_native.bpf.c:647 20: (15) if r0 == 0x0 goto pc+661 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) ; switch (*mode) { @ xdp_native.bpf.c:650 21: (61) r1 = *(u32 *)(r8 +0) ; frame1: R1_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) R8=map_value(map=map_xdp_setup,ks=4,vs=4) 22: (66) if w1 s> 0x1 goto pc+20 43: frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) R1=scalar(smin=umin=smin32=umin32=2,smax=umax=umax32=0x7fffffff,var_off=(0x0; 0x7fffffff)) R6=2 R7=ctx() R8=map_value(map=map_xdp_setup,ks=4,vs=4) R10=fp0 fp-336=????1 ; switch (*mode) { @ xdp_native.bpf.c:650 43: (16) if w1 == 0x2 goto pc+26 ; frame1: R1=scalar(smin=umin=smin32=umin32=3,smax=umax=umax32=0x7fffffff,var_off=(0x0; 0x7fffffff)) 44: (16) if w1 == 0x3 goto pc+123 168: frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) R1=3 R6=2 R7=ctx() R8=map_value(map=map_xdp_setup,ks=4,vs=4) R10=fp0 fp-336=????1 ; return xdp_adjst_tail(ctx, (__u16)(*port)); @ xdp_native.bpf.c:658 168: (61) r2 = *(u32 *)(r0 +0) ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) R2_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) ; udph = filter_udphdr(ctx, port); @ xdp_native.bpf.c:430 169: (54) w2 &= 65535 ; frame1: R2_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) 170: (bf) r1 = r7 ; frame1: R1_w=ctx() R7=ctx() 171: (85) call pc+512 caller: frame1: R6=2 R7=ctx() R8=map_value(map=map_xdp_setup,ks=4,vs=4) R10=fp0 fp-336=????1 callee: frame2: R1_w=ctx() R2_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R10=fp0 684: frame2: R1=ctx() R2=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R10=fp0 ; static struct udphdr *filter_udphdr(struct xdp_md *ctx, __u16 port) @ xdp_native.bpf.c:71 684: (bc) w6 = w2 ; frame2: R2=scalar(id=54,smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R6_w=scalar(id=54,smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) 685: (bf) r7 = r1 ; frame2: R1=ctx() R7_w=ctx() ; err = bpf_xdp_pull_data(ctx, sizeof(*eth)); @ xdp_native.bpf.c:78 686: (b4) w2 = 14 ; frame2: R2_w=14 687: (85) call bpf_xdp_pull_data#85514 ; frame2: R0_w=scalar() 688: (bc) w1 = w0 ; frame2: R0_w=scalar() R1_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) 689: (b7) r0 = 0 ; frame2: R0_w=0 ; if (err) @ xdp_native.bpf.c:79 690: (56) if w1 != 0x0 goto pc+55 ; frame2: R1_w=0 ; data_end = (void *)(long)ctx->data_end; @ xdp_native.bpf.c:82 691: (61) r2 = *(u32 *)(r7 +4) ; frame2: R2_w=pkt_end() R7_w=ctx() ; data = eth = (void *)(long)ctx->data; @ xdp_native.bpf.c:83 692: (61) r1 = *(u32 *)(r7 +0) ; frame2: R1_w=pkt(r=0) R7_w=ctx() ; if (data + sizeof(*eth) > data_end) @ xdp_native.bpf.c:85 693: (bf) r3 = r1 ; frame2: R1_w=pkt(r=0) R3_w=pkt(r=0) 694: (07) r3 += 14 ; frame2: R3=pkt(off=14,r=0) 695: (2d) if r3 > r2 goto pc+50 ; frame2: R2=pkt_end() R3=pkt(off=14,r=14) ; if (eth->h_proto == bpf_htons(ETH_P_IP)) { @ xdp_native.bpf.c:88 696: (71) r2 = *(u8 *)(r1 +12) ; frame2: R1=pkt(r=14) R2_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 697: (71) r1 = *(u8 *)(r1 +13) ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 698: (64) w1 <<= 8 ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xff00,var_off=(0x0; 0xff00)) 699: (4c) w1 |= w2 ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R2_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 700: (16) if w1 == 0xdd86 goto pc+15 ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) 701: (56) if w1 != 0x8 goto pc+44 ; frame2: R1_w=8 ; err = bpf_xdp_pull_data(ctx, sizeof(*eth) + sizeof(*iph) + @ xdp_native.bpf.c:91 702: (bf) r1 = r7 ; frame2: R1_w=ctx() R7=ctx() 703: (b4) w2 = 42 ; frame2: R2_w=42 704: (85) call bpf_xdp_pull_data#85514 ; frame2: R0=scalar() 705: (bc) w1 = w0 ; frame2: R0=scalar() R1_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) 706: (b7) r0 = 0 ; frame2: R0_w=0 ; if (err) @ xdp_native.bpf.c:93 707: (56) if w1 != 0x0 goto pc+38 ; frame2: R1_w=0 ; data_end = (void *)(long)ctx->data_end; @ xdp_native.bpf.c:96 708: (61) r1 = *(u32 *)(r7 +4) ; frame2: R1_w=pkt_end() R7=ctx() ; data = (void *)(long)ctx->data; @ xdp_native.bpf.c:97 709: (61) r2 = *(u32 *)(r7 +0) ; frame2: R2_w=pkt(r=0) R7=ctx() ; if (iph + 1 > (struct iphdr *)data_end || @ xdp_native.bpf.c:101 710: (bf) r7 = r2 ; frame2: R2_w=pkt(r=0) R7_w=pkt(r=0) 711: (07) r7 += 34 ; frame2: R7_w=pkt(off=34,r=0) 712: (2d) if r7 > r1 goto pc+33 ; frame2: R1_w=pkt_end() R7_w=pkt(off=34,r=34) ; iph->protocol != IPPROTO_UDP) @ xdp_native.bpf.c:102 713: (71) r2 = *(u8 *)(r2 +23) ; frame2: R2=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) ; if (iph + 1 > (struct iphdr *)data_end || @ xdp_native.bpf.c:101 714: (16) if w2 == 0x11 goto pc+14 729: frame2: R0=0 R1=pkt_end() R2=17 R6=scalar(id=54,smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R7=pkt(off=34,r=34) R10=fp0 ; if (udph + 1 > (struct udphdr *)data_end) @ xdp_native.bpf.c:128 729: (bf) r2 = r7 ; frame2: R2_w=pkt(off=34,r=34) R7=pkt(off=34,r=34) 730: (07) r2 += 8 ; frame2: R2=pkt(off=42,r=34) 731: (2d) if r2 > r1 goto pc+14 ; frame2: R1=pkt_end() R2=pkt(off=42,r=42) ; if (udph->dest != bpf_htons(port)) @ xdp_native.bpf.c:131 732: (dc) r6 = be16 r6 ; frame2: R6_w=scalar() 733: (69) r1 = *(u16 *)(r7 +2) ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R7=pkt(off=34,r=42) 734: (5e) if w1 != w6 goto pc+11 ; frame2: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=0xffff,var_off=(0x0; 0xffff)) R6_w=scalar(smax=0x7fffffff0000ffff,umax=0xffffffff0000ffff,smin32=0,smax32=umax32=0xffff,var_off=(0x0; 0xffffffff0000ffff)) 735: (b4) w1 = 0 ; frame2: R1_w=0 736: (63) *(u32 *)(r10 -4) = r1 ; frame2: R1_w=0 R10=fp0 fp-8=0000???? 737: (bf) r2 = r10 ; frame2: R2_w=fp0 R10=fp0 738: (07) r2 += -4 ; frame2: R2_w=fp-4 ; count = bpf_map_lookup_elem(&map_xdp_stats, &stat_type); @ xdp_native.bpf.c:65 739: (18) r1 = 0xff110001099ad200 ; frame2: R1_w=map_ptr(map=map_xdp_stats,ks=4,vs=8) 741: (85) call bpf_map_lookup_elem#1 ; frame2: R0=map_value(map=map_xdp_stats,ks=4,vs=8) ; if (count) @ xdp_native.bpf.c:67 742: (15) if r0 == 0x0 goto pc+2 ; frame2: R0=map_value(map=map_xdp_stats,ks=4,vs=8) 743: (b7) r1 = 1 ; frame2: R1_w=1 ; __sync_fetch_and_add(count, 1); @ xdp_native.bpf.c:68 744: (db) r1 = atomic64_fetch_add((u64 *)(r0 +0), r1) ; frame2: R0=map_value(map=map_xdp_stats,ks=4,vs=8) R1_w=scalar() 745: (bf) r0 = r7 ; frame2: R0_w=pkt(off=34,r=42) R7=pkt(off=34,r=42) ; } @ xdp_native.bpf.c:137 746: (95) exit returning from callee: frame2: R0_w=pkt(off=34,r=42) R1_w=scalar() R6=scalar(smax=0x7fffffff0000ffff,umax=0xffffffff0000ffff,smin32=0,smax32=umax32=0xffff,var_off=(0x0; 0xffffffff0000ffff)) R7=pkt(off=34,r=42) R10=fp0 fp-8=0000???? to caller at 172: frame1: R0_w=pkt(off=34,r=42) R6=2 R7=ctx() R8=map_value(map=map_xdp_setup,ks=4,vs=4) R10=fp0 fp-336=????1 ; udph = filter_udphdr(ctx, port); @ xdp_native.bpf.c:430 172: (bf) r8 = r0 ; frame1: R0_w=pkt(off=34,r=42) R8_w=pkt(off=34,r=42) ; if (!udph) @ xdp_native.bpf.c:431 173: (15) if r8 == 0x0 goto pc+508 ; frame1: R8_w=pkt(off=34,r=42) ; hdr_len = (void *)udph - (void *)(long)ctx->data + @ xdp_native.bpf.c:434 174: (61) r9 = *(u32 *)(r7 +0) ; frame1: R7=ctx() R9_w=pkt(r=0) ; key = XDP_ADJST_OFFSET; @ xdp_native.bpf.c:436 175: (63) *(u32 *)(r10 -328) = r6 ; frame1: R6=2 R10=fp0 fp-328=????2 176: (bf) r2 = r10 ; frame1: R2_w=fp0 R10=fp0 177: (07) r2 += -328 ; frame1: R2_w=fp-328 ; adjust_offset = bpf_map_lookup_elem(&map_xdp_setup, &key); @ xdp_native.bpf.c:437 178: (18) r1 = 0xff110001099ada00 ; frame1: R1_w=map_ptr(map=map_xdp_setup,ks=4,vs=4) 180: (85) call bpf_map_lookup_elem#1 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) ; if (!adjust_offset) @ xdp_native.bpf.c:438 181: (15) if r0 == 0x0 goto pc+500 ; frame1: R0=map_value(map=map_xdp_setup,ks=4,vs=4) 182: (63) *(u32 *)(r10 -344) = r9 invalid size of register spill processed 2736 insns (limit 1000000) max_states_per_insn 5 total_states 190 peak_states 156 mark_read 19 -- END PROG LOAD LOG -- libbpf: prog 'xdp_prog': failed to load: -13 libbpf: failed to load object '/root/ksft-net-drv/net/lib/xdp_native.bpf.o' tools/testing/selftests/net/lib/xdp_native.bpf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/net/lib/xdp_native.bpf.c b/tools/testing/selftests/net/lib/xdp_native.bpf.c index c368fc045f4b..64f05229ab24 100644 --- a/tools/testing/selftests/net/lib/xdp_native.bpf.c +++ b/tools/testing/selftests/net/lib/xdp_native.bpf.c @@ -332,7 +332,7 @@ static __u16 csum_fold_helper(__u32 csum) } static int xdp_adjst_tail_shrnk_data(struct xdp_md *ctx, __u16 offset, - __u32 hdr_len) + unsigned long hdr_len) { char tmp_buff[MAX_ADJST_OFFSET]; __u32 buff_pos, udp_csum = 0; @@ -422,8 +422,9 @@ static int xdp_adjst_tail(struct xdp_md *ctx, __u16 port) { struct udphdr *udph = NULL; __s32 *adjust_offset, *val; - __u32 key, hdr_len; + unsigned long hdr_len; void *offset_ptr; + __u32 key; __u8 tag; int ret; -- 2.47.3

1 month, 4 weeks

[PATCH v4 0/2] libbpf: fix BTF dedup to support recursive typedef

by Paul Houssel

Pahole fails to encode BTF for some Go projects (e.g. Kubernetes and Podman) due to recursive type definitions that create reference loops not representable in C. These recursive typedefs trigger a failure in the BTF deduplication algorithm. This patch extends btf_dedup_struct_types() to properly handle potential recursion for BTF_KIND_TYPEDEF, similar to how recursion is already handled for BTF_KIND_STRUCT. This allows pahole to successfully generate BTF for Go binaries using recursive types without impacting existing C-based workflows. Changes in v4: fix typo found by Claude-based CI Changes in v3: 1. Patch 1: Adjusted the comment of btf_dedup_ref_type() to refer to typedef as well. 2. Patch 2: Update of the "dedup: recursive typedef" test to include a duplicated version of the types to make sure deduplication still happens in this case. Changes in v2: 1. Patch 1: Refactored code to prevent copying existing logic. Instead of adding a new function we modify the existing btf_dedup_struct_type() function to handle the BTF_KIND_TYPEDEF case. Calls to btf_hash_struct() and btf_shallow_equal_struct() are replaced with calls to functions that select btf_hash_struct() / btf_hash_typedef() based on the type. 2. Patch 2: Added tests v3: https://lore.kernel.org/lkml/cover.1763024337.git.paul.houssel@orange.com/ v2: https://lore.kernel.org/lkml/cover.1762956564.git.paul.houssel@orange.com/ v1: https://lore.kernel.org/lkml/20251107153408.159342-1-paulhoussel2@gmail.com/ Paul Houssel (2): libbpf: fix BTF dedup to support recursive typedef definitions selftests/bpf: add BTF dedup tests for recursive typedef definitions tools/lib/bpf/btf.c | 71 +++++++++++++++----- tools/testing/selftests/bpf/prog_tests/btf.c | 65 ++++++++++++++++++ 2 files changed, 120 insertions(+), 16 deletions(-) -- 2.51.0

1 month, 4 weeks

[RFC PATCH v1 00/37] guest_memfd: In-place conversion support

by Ackerley Tng

Hello, IIUC this is the first independent patch series for guest_memfd's in-place conversion series! Happy to finally bring this out on its own. Previous versions of this feature, part of other series, are available at [1][2][3]. Many prior discussions have led up to these main features of this series, and these are the main points I'd like feedback on. 1. Having private/shared status stored in a maple tree (Thanks Michael for your support of using maple trees over xarrays for performance! [4]). 2. Having a new guest_memfd ioctl (not a vm ioctl) that performs conversions. 3. Using ioctls/structs/input attribute similar to the existing vm ioctl KVM_SET_MEMORY_ATTRIBUTES to perform conversions. 4. Storing requested attributes directly in the maple tree. 5. Using a KVM module-wide param to toggle between setting memory attributes via vm and guest_memfd ioctls (making them mututally exclusive - a single loaded KVM module can only do one of the two.) 6. Skipping LRU in guest_memfd folios - make guest_memfd folios not participate in LRU to avoid LRU refcounts from interfering with conversions. This series is based on kvm/next, followed by + v12 of NUMA mempolicy support patches [5] + 3 cleanup patches from Sean [6][7][8] Everything is stitched together here for your convenience https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-co… Thank you all for helping with this series! If I missed out your comment from a previous series, it's not intentional! Please do raise it again. TODOs: + There might be an issue with memory failure handling because when guest_memfd folios stop participating in LRU. From a preliminary analysis, HWPoisonHandlable() is only true if PageLRU() is true. This needs further investigation. [1] https://lore.kernel.org/all/bd163de3118b626d1005aa88e71ef2fb72f0be0f.172600… [2] https://lore.kernel.org/all/20250117163001.2326672-6-tabba@google.com/ [3] https://lore.kernel.org/all/b784326e9ccae6a08388f1bf39db70a2204bdc51.174726… [4] https://lore.kernel.org/all/20250529054227.hh2f4jmyqf6igd3i@amd.com/ [5] https://lore.kernel.org/all/20251007221420.344669-1-seanjc@google.com/T/ [6] https://lore.kernel.org/all/20250924174255.2141847-1-seanjc@google.com/ [7] https://lore.kernel.org/all/20251007224515.374516-1-seanjc@google.com/ [8] https://lore.kernel.org/all/20251007223625.369939-1-seanjc@google.com/ Ackerley Tng (19): KVM: guest_memfd: Update kvm_gmem_populate() to use gmem attributes KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 KVM: guest_memfd: Don't set FGP_ACCESSED when getting folios KVM: guest_memfd: Skip LRU for guest_memfd folios KVM: guest_memfd: Add support for KVM_SET_MEMORY_ATTRIBUTES KVM: selftests: Update framework to use KVM_SET_MEMORY_ATTRIBUTES2 KVM: selftests: guest_memfd: Test basic single-page conversion flow KVM: selftests: guest_memfd: Test conversion flow when INIT_SHARED KVM: selftests: guest_memfd: Test indexing in guest_memfd KVM: selftests: guest_memfd: Test conversion before allocation KVM: selftests: guest_memfd: Convert with allocated folios in different layouts KVM: selftests: guest_memfd: Test precision of conversion KVM: selftests: guest_memfd: Test that truncation does not change shared/private status KVM: selftests: guest_memfd: Test conversion with elevated page refcount KVM: selftests: Reset shared memory after hole-punching KVM: selftests: Provide function to look up guest_memfd details from gpa KVM: selftests: Make TEST_EXPECT_SIGBUS thread-safe KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd KVM: selftests: Add script to exercise private_mem_conversions_test Sean Christopherson (18): KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings KVM: Rename KVM_GENERIC_MEMORY_ATTRIBUTES to KVM_VM_MEMORY_ATTRIBUTES KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined KVM: Stub in ability to disable per-VM memory attribute tracking KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs KVM: Move KVM_VM_MEMORY_ATTRIBUTES config definition to x86 KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes KVM: selftests: Create gmem fd before "regular" fd when adding memslot KVM: selftests: Rename guest_memfd{,_offset} to gmem_{fd,offset} KVM: selftests: Add support for mmap() on guest_memfd in core library KVM: selftests: Add helpers for calling ioctls on guest_memfd KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes KVM: selftests: Add selftests global for guest memory attributes capability KVM: selftests: Provide common function to set memory attributes KVM: selftests: Check fd/flags provided to mmap() when setting up memslot KVM: selftests: Update pre-fault test to work with per-guest_memfd attributes KVM: selftests: Update private memory exits test work with per-gmem attributes Documentation/virt/kvm/api.rst | 72 ++- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/Kconfig | 15 +- arch/x86/kvm/mmu/mmu.c | 4 +- arch/x86/kvm/x86.c | 13 +- include/linux/kvm_host.h | 44 +- include/trace/events/kvm.h | 4 +- include/uapi/linux/kvm.h | 17 + mm/filemap.c | 1 + mm/memcontrol.c | 2 + tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile.kvm | 1 + .../kvm/guest_memfd_conversions_test.c | 498 ++++++++++++++++++ .../testing/selftests/kvm/include/kvm_util.h | 127 ++++- .../testing/selftests/kvm/include/test_util.h | 29 +- tools/testing/selftests/kvm/lib/kvm_util.c | 128 +++-- tools/testing/selftests/kvm/lib/test_util.c | 7 - .../selftests/kvm/pre_fault_memory_test.c | 2 +- .../kvm/x86/private_mem_conversions_test.c | 55 +- .../kvm/x86/private_mem_conversions_test.py | 159 ++++++ .../kvm/x86/private_mem_kvm_exits_test.c | 36 +- virt/kvm/Kconfig | 4 +- virt/kvm/guest_memfd.c | 414 +++++++++++++-- virt/kvm/kvm_main.c | 104 +++- 24 files changed, 1554 insertions(+), 185 deletions(-) create mode 100644 tools/testing/selftests/kvm/guest_memfd_conversions_test.c create mode 100755 tools/testing/selftests/kvm/x86/private_mem_conversions_test.py -- 2.51.0.858.gf9c4a03a3a-goog

1 month, 4 weeks

[PATCH v2] selftests/cgroup: conform test to KTAP format output

by Guopeng Zhang

Conform the layout, informational and status messages to KTAP. No functional change is intended other than the layout of output messages. Signed-off-by: Guopeng Zhang <zhangguopeng(a)kylinos.cn> Suggested-by: Sebastian Chlad <sebastian.chlad(a)suse.com> --- v2: Change subject and commit message to refer to KTAP instead of TAP. No code changes. --- tools/testing/selftests/cgroup/test_core.c | 7 ++++--- tools/testing/selftests/cgroup/test_cpu.c | 7 ++++--- tools/testing/selftests/cgroup/test_cpuset.c | 7 ++++--- tools/testing/selftests/cgroup/test_freezer.c | 7 ++++--- tools/testing/selftests/cgroup/test_kill.c | 7 ++++--- tools/testing/selftests/cgroup/test_kmem.c | 7 ++++--- tools/testing/selftests/cgroup/test_memcontrol.c | 7 ++++--- tools/testing/selftests/cgroup/test_zswap.c | 7 ++++--- 8 files changed, 32 insertions(+), 24 deletions(-) diff --git a/tools/testing/selftests/cgroup/test_core.c b/tools/testing/selftests/cgroup/test_core.c index 5e5b8c4b8c0e..102262555a59 100644 --- a/tools/testing/selftests/cgroup/test_core.c +++ b/tools/testing/selftests/cgroup/test_core.c @@ -923,8 +923,10 @@ struct corecg_test { int main(int argc, char *argv[]) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), &nsdelegate)) { if (setup_named_v1_root(root, sizeof(root), CG_NAMED_NAME)) ksft_exit_skip("cgroup v2 isn't mounted and could not setup named v1 hierarchy\n"); @@ -946,12 +948,11 @@ int main(int argc, char *argv[]) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } cleanup_named_v1_root(root); - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_cpu.c b/tools/testing/selftests/cgroup/test_cpu.c index 7d77d3d43c8e..c83f05438d7c 100644 --- a/tools/testing/selftests/cgroup/test_cpu.c +++ b/tools/testing/selftests/cgroup/test_cpu.c @@ -796,8 +796,10 @@ struct cpucg_test { int main(int argc, char *argv[]) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -814,11 +816,10 @@ int main(int argc, char *argv[]) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_cpuset.c b/tools/testing/selftests/cgroup/test_cpuset.c index 8094091a5857..c5cf8b56ceb8 100644 --- a/tools/testing/selftests/cgroup/test_cpuset.c +++ b/tools/testing/selftests/cgroup/test_cpuset.c @@ -247,8 +247,10 @@ struct cpuset_test { int main(int argc, char *argv[]) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -265,11 +267,10 @@ int main(int argc, char *argv[]) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_freezer.c b/tools/testing/selftests/cgroup/test_freezer.c index 714c963aa3f5..97fae92c8387 100644 --- a/tools/testing/selftests/cgroup/test_freezer.c +++ b/tools/testing/selftests/cgroup/test_freezer.c @@ -1488,8 +1488,10 @@ struct cgfreezer_test { int main(int argc, char *argv[]) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); for (i = 0; i < ARRAY_SIZE(tests); i++) { @@ -1501,11 +1503,10 @@ int main(int argc, char *argv[]) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_kill.c b/tools/testing/selftests/cgroup/test_kill.c index a4dd326ced79..c8c9d306925b 100644 --- a/tools/testing/selftests/cgroup/test_kill.c +++ b/tools/testing/selftests/cgroup/test_kill.c @@ -274,8 +274,10 @@ struct cgkill_test { int main(int argc, char *argv[]) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); for (i = 0; i < ARRAY_SIZE(tests); i++) { @@ -287,11 +289,10 @@ int main(int argc, char *argv[]) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 005a142f3492..ca38525484e3 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -421,8 +421,10 @@ struct kmem_test { int main(int argc, char **argv) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -446,11 +448,10 @@ int main(int argc, char **argv) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index 2e9d78ab641c..4e1647568c5b 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -1650,8 +1650,10 @@ struct memcg_test { int main(int argc, char **argv) { char root[PATH_MAX]; - int i, proc_status, ret = EXIT_SUCCESS; + int i, proc_status; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -1685,11 +1687,10 @@ int main(int argc, char **argv) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c index ab865d900791..64ebc3f3f203 100644 --- a/tools/testing/selftests/cgroup/test_zswap.c +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -597,8 +597,10 @@ static bool zswap_configured(void) int main(int argc, char **argv) { char root[PATH_MAX]; - int i, ret = EXIT_SUCCESS; + int i; + ksft_print_header(); + ksft_set_plan(ARRAY_SIZE(tests)); if (cg_find_unified_root(root, sizeof(root), NULL)) ksft_exit_skip("cgroup v2 isn't mounted\n"); @@ -625,11 +627,10 @@ int main(int argc, char **argv) ksft_test_result_skip("%s\n", tests[i].name); break; default: - ret = EXIT_FAILURE; ksft_test_result_fail("%s\n", tests[i].name); break; } } - return ret; + ksft_finished(); } -- 2.25.1

1 month, 4 weeks

[PATCH bpf-next v2] selftests/bpf: Fix htab_update/reenter_update selftest failure

by Saket Kumar Bhaskar

Since commit 31158ad02ddb ("rqspinlock: Add deadlock detection and recovery") the updated path on re-entrancy now reports deadlock via -EDEADLK instead of the previous -EBUSY. Also, the way reentrancy was exercised (via fentry/lookup_elem_raw) has been fragile because lookup_elem_raw may be inlined (find_kernel_btf_id() will return -ESRCH). To fix this fentry is attached to bpf_obj_free_fields() instead of lookup_elem_raw() and: - The htab map is made to use a BTF-described struct val with a struct bpf_timer so that check_and_free_fields() reliably calls bpf_obj_free_fields() on element replacement. - The selftest is updated to do two updates to the same key (insert + replace) in prog_test. - The selftest is updated to align with expected errno with the kernel’s current behavior. Signed-off-by: Saket Kumar Bhaskar <skb99(a)linux.ibm.com> --- Changes since v1: Addressed comments from Alexei: * Fixed the scenario where test may fail when lookup_elem_raw() is inlined. v1: https://lore.kernel.org/all/20251106052628.349117-1-skb99@linux.ibm.com/ .../selftests/bpf/prog_tests/htab_update.c | 38 ++++++++++++++----- .../testing/selftests/bpf/progs/htab_update.c | 19 +++++++--- 2 files changed, 41 insertions(+), 16 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/htab_update.c b/tools/testing/selftests/bpf/prog_tests/htab_update.c index 2bc85f4814f4..96b65c1a321a 100644 --- a/tools/testing/selftests/bpf/prog_tests/htab_update.c +++ b/tools/testing/selftests/bpf/prog_tests/htab_update.c @@ -15,17 +15,17 @@ struct htab_update_ctx { static void test_reenter_update(void) { struct htab_update *skel; - unsigned int key, value; + void *value = NULL; + unsigned int key, value_size; int err; skel = htab_update__open(); if (!ASSERT_OK_PTR(skel, "htab_update__open")) return; - /* lookup_elem_raw() may be inlined and find_kernel_btf_id() will return -ESRCH */ - bpf_program__set_autoload(skel->progs.lookup_elem_raw, true); + bpf_program__set_autoload(skel->progs.bpf_obj_free_fields, true); err = htab_update__load(skel); - if (!ASSERT_TRUE(!err || err == -ESRCH, "htab_update__load") || err) + if (!ASSERT_TRUE(!err, "htab_update__load") || err) goto out; skel->bss->pid = getpid(); @@ -33,14 +33,32 @@ static void test_reenter_update(void) if (!ASSERT_OK(err, "htab_update__attach")) goto out; - /* Will trigger the reentrancy of bpf_map_update_elem() */ - key = 0; - value = 0; - err = bpf_map_update_elem(bpf_map__fd(skel->maps.htab), &key, &value, 0); - if (!ASSERT_OK(err, "add element")) + value_size = bpf_map__value_size(skel->maps.htab); + + value = calloc(1, value_size); + if (!ASSERT_OK_PTR(value, "calloc value")) + goto out; + /* + * First update: plain insert. This should NOT trigger the re-entrancy + * path, because there is no old element to free yet. + */ + err = bpf_map_update_elem(bpf_map__fd(skel->maps.htab), &key, &value, BPF_ANY); + if (!ASSERT_OK(err, "first update (insert)")) + goto out; + + /* + * Second update: replace existing element with same key and trigger + * the reentrancy of bpf_map_update_elem(). + * check_and_free_fields() calls bpf_obj_free_fields() on the old + * value, which is where fentry program runs and performs a nested + * bpf_map_update_elem(), triggering -EDEADLK. + */ + memset(&value, 0, sizeof(value)); + err = bpf_map_update_elem(bpf_map__fd(skel->maps.htab), &key, &value, BPF_ANY); + if (!ASSERT_OK(err, "second update (replace)")) goto out; - ASSERT_EQ(skel->bss->update_err, -EBUSY, "no reentrancy"); + ASSERT_EQ(skel->bss->update_err, -EDEADLK, "no reentrancy"); out: htab_update__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/htab_update.c b/tools/testing/selftests/bpf/progs/htab_update.c index 7481bb30b29b..195d3b2fba00 100644 --- a/tools/testing/selftests/bpf/progs/htab_update.c +++ b/tools/testing/selftests/bpf/progs/htab_update.c @@ -6,24 +6,31 @@ char _license[] SEC("license") = "GPL"; +/* Map value type: has BTF-managed field (bpf_timer) */ +struct val { + struct bpf_timer t; + __u64 payload; +}; + struct { __uint(type, BPF_MAP_TYPE_HASH); __uint(max_entries, 1); - __uint(key_size, sizeof(__u32)); - __uint(value_size, sizeof(__u32)); + __type(key, __u32); + __type(value, struct val); } htab SEC(".maps"); int pid = 0; int update_err = 0; -SEC("?fentry/lookup_elem_raw") -int lookup_elem_raw(void *ctx) +SEC("?fentry/bpf_obj_free_fields") +int bpf_obj_free_fields(void *ctx) { - __u32 key = 0, value = 1; + __u32 key = 0; + struct val value = { .payload = 1 }; if ((bpf_get_current_pid_tgid() >> 32) != pid) return 0; - update_err = bpf_map_update_elem(&htab, &key, &value, 0); + update_err = bpf_map_update_elem(&htab, &key, &value, BPF_ANY); return 0; } -- 2.51.0

1 month, 4 weeks

[PATCH v2 0/4] KVM: selftests: arm64: Improve diagnostics from set_id_regs

by Mark Brown

While debugging issues related to aarch64 only systems I ran into speedbumps due to the lack of detail in the results reported when the guest register read and reset value preservation tests were run, they generated an immediately fatal assert without indicating which register was being tested. Update these tests to report a result per register, making it much easier to see what the problem being reported is. A similar, though less severe, issue exists with the validation of the individual bitfields in registers due to the use of immediately fatal asserts. Update those asserts to be standard kselftest reports. Finally we have a fix for spurious errors on some NV systems. Signed-off-by: Mark Brown <broonie(a)kernel.org> --- Changes in v2: - Add a fix for spurious failures with 64 bit only guests. - Link to v1: https://patch.msgid.link/20251030-kvm-arm64-set-id-regs-aarch64-v1-0-96fe0d… --- Mark Brown (4): KVM: selftests: arm64: Report set_id_reg reads of test registers as tests KVM: selftests: arm64: Report register reset tests individually KVM: selftests: arm64: Make set_id_regs bitfield validatity checks non-fatal KVM: selftests: arm64: Skip all 32 bit IDs when set_id_regs is aarch64 only tools/testing/selftests/kvm/arm64/set_id_regs.c | 150 ++++++++++++++++++------ 1 file changed, 111 insertions(+), 39 deletions(-) --- base-commit: 211ddde0823f1442e4ad052a2f30f050145ccada change-id: 20251028-kvm-arm64-set-id-regs-aarch64-ebb77969401c Best regards, -- Mark Brown <broonie(a)kernel.org>

2 months

[PATCH v7 0/2] KVM: guest_memfd: use write for population

by Kalyazin, Nikita

On systems that support shared guest memory, write() is useful, for example, for population of the initial image. Even though the same can also be achieved via userspace mapping and memcpying from userspace, write() provides a more performant option because it does not need to set user page tables and it does not cause a page fault for every page like memcpy would. Note that memcpy cannot be accelerated via MADV_POPULATE_WRITE as it is not supported by guest_memfd and relies on GUP. Populating 512MiB of guest_memfd on a x86 machine: - via memcpy: 436 ms - via write: 202 ms (-54%) Only PAGE_ALIGNED offset and len are allowed. Even though non-aligned writes are technically possible, when in-place conversion support is implemented [1], the restriction makes handling of mixed shared/private huge pages simpler. write() will only be allowed to populate shared pages. When direct map removal is implemented [2] - write() will not be allowed to access pages that have already been removed from direct map - on completion, write() will remove the populated pages from direct map While it is technically possible to implement read() syscall on systems with shared guest memory, it is not supported as there is currently no use case for it. [1] https://lore.kernel.org/kvm/cover.1760731772.git.ackerleytng@google.com [2] https://lore.kernel.org/kvm/20250924151101.2225820-1-patrick.roy@campus.lmu… Nikita Kalyazin (2): KVM: guest_memfd: add generic population via write KVM: selftests: update guest_memfd write tests Documentation/virt/kvm/api.rst | 2 + include/linux/kvm_host.h | 2 +- include/uapi/linux/kvm.h | 1 + .../testing/selftests/kvm/guest_memfd_test.c | 58 +++++++++++++++++-- virt/kvm/guest_memfd.c | 52 +++++++++++++++++ 5 files changed, 108 insertions(+), 7 deletions(-) base-commit: 8a4821412cf2c1429fffa07c012dd150f2edf78c -- 2.50.1

2 months

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-kselftest-mirror