Since GITS_TYPER.PTA == 0, the ITS MAPC command demands a CPU ID, rather than a physical redistributor address, for its RDbase command argument.
As such, when MAPC-ing guest ITS collections, vgic_lpi_stress iterates over CPU IDs in the range [0, nr_cpus), passing them as the RDbase vcpu_id argument to its_send_mapc_cmd().
However, its_encode_target() in the its_send_mapc_cmd() selftest handler expects RDbase arguments to have a 16 bit offset, as shown by the 16-bit target_addr right shift its implementation:
its_mask_encode(&cmd->raw_cmd[2], target_addr >> 16, 51, 16)
At the moment, all CPU IDs passed into its_send_mapc_cmd() have no offset, therefore becoming 0x0 after the bit shift. Thus, when vgic_its_cmd_handle_mapc() receives the ITS command in vgic-its.c, it always interprets the RDbase target CPU as CPU 0. All interrupts sent to collections will be processed by vCPU 0, which defeats the purpose of this multi-vCPU test.
Fix by creating procnum_to_rdbase() helper function, which left-shifts the vCPU parameter received by its_send_mapc_cmd 16 bits before passing it to its_encode_target for encoding.
Signed-off-by: Maximilian Dittgen mdittgen@amazon.de --- This patch has already been merged as a fix in Linux 6.18-rc6 as a24f7af. --- tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c b/tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c index aec1b69a4de3..7f9fdcf42ae6 100644 --- a/tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c +++ b/tools/testing/selftests/kvm/lib/arm64/gic_v3_its.c @@ -15,6 +15,8 @@ #include "gic_v3.h" #include "processor.h"
+#define GITS_COLLECTION_TARGET_SHIFT 16 + static u64 its_read_u64(unsigned long offset) { return readq_relaxed(GITS_BASE_GVA + offset); @@ -163,6 +165,11 @@ static void its_encode_collection(struct its_cmd_block *cmd, u16 col) its_mask_encode(&cmd->raw_cmd[2], col, 15, 0); }
+static u64 procnum_to_rdbase(u32 vcpu_id) +{ + return vcpu_id << GITS_COLLECTION_TARGET_SHIFT; +} + #define GITS_CMDQ_POLL_ITERATIONS 0
static void its_send_cmd(void *cmdq_base, struct its_cmd_block *cmd) @@ -217,7 +224,7 @@ void its_send_mapc_cmd(void *cmdq_base, u32 vcpu_id, u32 collection_id, bool val
its_encode_cmd(&cmd, GITS_CMD_MAPC); its_encode_collection(&cmd, collection_id); - its_encode_target(&cmd, vcpu_id); + its_encode_target(&cmd, procnum_to_rdbase(vcpu_id)); its_encode_valid(&cmd, valid);
its_send_cmd(cmdq_base, &cmd);