June 2024 - Linux-kselftest-mirror

[PATCH 0/5] riscv: add support for Zaamo and Zalrsc extensions

by Clément Léger

Since commit e87412e621f1 ("integrate Zaamo and Zalrsc text (#1304)"), the A extension has been described as a set of instructions provided by Zaamo and Zalrsc. Add these two extensions. This series is based on the Zc one [1]. Link: https://lore.kernel.org/linux-riscv/20240619113529.676940-1-cleger@rivosinc… --- Clément Léger (5): dt-bindings: riscv: add Zaamo and Zalrsc ISA extension description riscv: add parsing for Zaamo and Zalrsc extensions riscv: hwprobe: export Zaamo and Zalrsc extensions RISC-V: KVM: Allow Zaamo/Zalrsc extensions for Guest/VM KVM: riscv: selftests: Add Zaamo/Zalrsc extensions to get-reg-list test Documentation/arch/riscv/hwprobe.rst | 8 ++++++++ .../devicetree/bindings/riscv/extensions.yaml | 19 +++++++++++++++++++ arch/riscv/include/asm/hwcap.h | 2 ++ arch/riscv/include/uapi/asm/hwprobe.h | 2 ++ arch/riscv/include/uapi/asm/kvm.h | 2 ++ arch/riscv/kernel/cpufeature.c | 9 ++++++++- arch/riscv/kernel/sys_hwprobe.c | 2 ++ arch/riscv/kvm/vcpu_onereg.c | 4 ++++ .../selftests/kvm/riscv/get-reg-list.c | 8 ++++++++ 9 files changed, 55 insertions(+), 1 deletion(-) -- 2.45.2

4 days, 19 hours

4
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[PATCH v4] memfd: `MFD_NOEXEC_SEAL` should not imply `MFD_ALLOW_SEALING`

by Barnabás Pőcze

`MFD_NOEXEC_SEAL` should remove the executable bits and set `F_SEAL_EXEC` to prevent further modifications to the executable bits as per the comment in the uapi header file: not executable and sealed to prevent changing to executable However, commit 105ff5339f498a ("mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC") that introduced this feature made it so that `MFD_NOEXEC_SEAL` unsets `F_SEAL_SEAL`, essentially acting as a superset of `MFD_ALLOW_SEALING`. Nothing implies that it should be so, and indeed up until the second version of the of the patchset[0] that introduced `MFD_EXEC` and `MFD_NOEXEC_SEAL`, `F_SEAL_SEAL` was not removed, however, it was changed in the third revision of the patchset[1] without a clear explanation. This behaviour is surprising for application developers, there is no documentation that would reveal that `MFD_NOEXEC_SEAL` has the additional effect of `MFD_ALLOW_SEALING`. Additionally, combined with `vm.memfd_noexec=2` it has the effect of making all memfds initially sealable. So do not remove `F_SEAL_SEAL` when `MFD_NOEXEC_SEAL` is requested, thereby returning to the pre-Linux 6.3 behaviour of only allowing sealing when `MFD_ALLOW_SEALING` is specified. Now, this is technically a uapi break. However, the damage is expected to be minimal. To trigger user visible change, a program has to do the following steps: - create memfd: - with `MFD_NOEXEC_SEAL`, - without `MFD_ALLOW_SEALING`; - try to add seals / check the seals. But that seems unlikely to happen intentionally since this change essentially reverts the kernel's behaviour to that of Linux <6.3, so if a program worked correctly on those older kernels, it will likely work correctly after this change. I have used Debian Code Search and GitHub to try to find potential breakages, and I could only find a single one. dbus-broker's memfd_create() wrapper is aware of this implicit `MFD_ALLOW_SEALING` behaviour, and tries to work around it[2]. This workaround will break. Luckily, this only affects the test suite, it does not affect the normal operations of dbus-broker. There is a PR with a fix[3]. I also carried out a smoke test by building a kernel with this change and booting an Arch Linux system into GNOME and Plasma sessions. There was also a previous attempt to address this peculiarity by introducing a new flag[4]. [0]: https://lore.kernel.org/lkml/20220805222126.142525-3-jeffxu@google.com/ [1]: https://lore.kernel.org/lkml/20221202013404.163143-3-jeffxu@google.com/ [2]: https://github.com/bus1/dbus-broker/blob/9eb0b7e5826fc76cad7b025bc46f267d4a… [3]: https://github.com/bus1/dbus-broker/pull/366 [4]: https://lore.kernel.org/lkml/20230714114753.170814-1-david@readahead.eu/ Cc: stable(a)vger.kernel.org Signed-off-by: Barnabás Pőcze <pobrn(a)protonmail.com> --- * v3: https://lore.kernel.org/linux-mm/20240611231409.3899809-1-jeffxu@chromium.o… * v2: https://lore.kernel.org/linux-mm/20240524033933.135049-1-jeffxu@google.com/ * v1: https://lore.kernel.org/linux-mm/20240513191544.94754-1-pobrn@protonmail.co… This fourth version returns to removing the inconsistency as opposed to documenting its existence, with the same code change as v1 but with a somewhat extended commit message. This is sent because I believe it is worth at least a try; it can be easily reverted if bigger application breakages are discovered than initially imagined. --- mm/memfd.c | 9 ++++----- tools/testing/selftests/memfd/memfd_test.c | 2 +- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 7d8d3ab3fa37..8b7f6afee21d 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -356,12 +356,11 @@ SYSCALL_DEFINE2(memfd_create, inode->i_mode &= ~0111; file_seals = memfd_file_seals_ptr(file); - if (file_seals) { - *file_seals &= ~F_SEAL_SEAL; + if (file_seals) *file_seals |= F_SEAL_EXEC; - } - } else if (flags & MFD_ALLOW_SEALING) { - /* MFD_EXEC and MFD_ALLOW_SEALING are set */ + } + + if (flags & MFD_ALLOW_SEALING) { file_seals = memfd_file_seals_ptr(file); if (file_seals) *file_seals &= ~F_SEAL_SEAL; diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 95af2d78fd31..7b78329f65b6 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -1151,7 +1151,7 @@ static void test_noexec_seal(void) mfd_def_size, MFD_CLOEXEC | MFD_NOEXEC_SEAL); mfd_assert_mode(fd, 0666); - mfd_assert_has_seals(fd, F_SEAL_EXEC); + mfd_assert_has_seals(fd, F_SEAL_SEAL | F_SEAL_EXEC); mfd_fail_chmod(fd, 0777); close(fd); } -- 2.45.2

2 weeks, 4 days

4
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[PATCH v3 0/5] Add support for the Idle HLT intercept feature

by Manali Shukla

The upcoming new Idle HLT Intercept feature allows for the HLT instruction execution by a vCPU to be intercepted by the hypervisor only if there are no pending V_INTR and V_NMI events for the vCPU. When the vCPU is expected to service the pending V_INTR and V_NMI events, the Idle HLT intercept won’t trigger. The feature allows the hypervisor to determine if the vCPU is actually idle and reduces wasteful VMEXITs. Presence of the Idle HLT Intercept feature is indicated via CPUID function Fn8000_000A_EDX[30]. Document for the Idle HLT intercept feature is available at [1]. [1]: AMD64 Architecture Programmer's Manual Pub. 24593, April 2024, Vol 2, 15.9 Instruction Intercepts (Table 15-7: IDLE_HLT). https://bugzilla.kernel.org/attachment.cgi?id=306250 Testing Done: - Added a selftest to test the Idle HLT intercept functionality. - Compile and functionality testing for the Idle HLT intercept selftest are only done for x86_64. - Tested SEV and SEV-ES guest for the Idle HLT intercept functionality. v2 -> v3 - Incorporated Andrew's suggestion to structure vcpu_stat_types in a way that each architecture can share the generic types and also provide its own. v1 -> v2 - Done changes in svm_idle_hlt_test based on the review comments from Sean. - Added an enum based approach to get binary stats in vcpu_get_stat() which doesn't use string to get stat data based on the comments from Sean. - Added self_halt() and cli() helpers based on the comments from Sean. Manali Shukla (5): x86/cpufeatures: Add CPUID feature bit for Idle HLT intercept KVM: SVM: Add Idle HLT intercept support KVM: selftests: Add safe_halt() and cli() helpers to common code KVM: selftests: Add an interface to read the data of named vcpu stat KVM: selftests: KVM: SVM: Add Idle HLT intercept test arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/svm.h | 1 + arch/x86/include/uapi/asm/svm.h | 2 + arch/x86/kvm/svm/svm.c | 11 ++- tools/testing/selftests/kvm/Makefile | 1 + .../testing/selftests/kvm/include/kvm_util.h | 44 +++++++++ .../kvm/include/x86_64/kvm_util_arch.h | 40 +++++++++ .../selftests/kvm/include/x86_64/processor.h | 18 ++++ tools/testing/selftests/kvm/lib/kvm_util.c | 32 +++++++ .../selftests/kvm/x86_64/svm_idle_hlt_test.c | 89 +++++++++++++++++++ 10 files changed, 236 insertions(+), 3 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/svm_idle_hlt_test.c base-commit: d91a9cc16417b8247213a0144a1f0fd61dc855dd -- 2.34.1

2 months

5
20
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[PATCH 0/2] selftest: rtc: Add rtc feature detection and rtc file check

by Joseph Jang

1. In order to make rtctest more explicit and robust, we propose to use RTC_PARAM_GET ioctl interface to check rtc alarm feature state before running alarm related tests. 2. The rtctest requires the read permission on /dev/rtc0. The rtctest will be skipped if the /dev/rtc0 is not readable. Joseph Jang (2): selftest: rtc: Add to check rtc alarm status for alarm related test selftest: rtc: Check if could access /dev/rtc0 before testing tools/testing/selftests/rtc/Makefile | 2 +- tools/testing/selftests/rtc/rtctest.c | 71 ++++++++++++++++++++++++++- 2 files changed, 71 insertions(+), 2 deletions(-) -- 2.34.1

2 months

3
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[PATCH v2 00/25] Enable FRED with KVM VMX

by Xin Li

This patch set enables the Intel flexible return and event delivery (FRED) architecture with KVM VMX to allow guests to utilize FRED. The FRED architecture defines simple new transitions that change privilege level (ring transitions). The FRED architecture was designed with the following goals: 1) Improve overall performance and response time by replacing event delivery through the interrupt descriptor table (IDT event delivery) and event return by the IRET instruction with lower latency transitions. 2) Improve software robustness by ensuring that event delivery establishes the full supervisor context and that event return establishes the full user context. The new transitions defined by the FRED architecture are FRED event delivery and, for returning from events, two FRED return instructions. FRED event delivery can effect a transition from ring 3 to ring 0, but it is used also to deliver events incident to ring 0. One FRED instruction (ERETU) effects a return from ring 0 to ring 3, while the other (ERETS) returns while remaining in ring 0. Collectively, FRED event delivery and the FRED return instructions are FRED transitions. Intel VMX architecture is extended to run FRED guests, and the major changes are: 1) New VMCS fields for FRED context management, which includes two new event data VMCS fields, eight new guest FRED context VMCS fields and eight new host FRED context VMCS fields. 2) VMX nested-exception support for proper virtualization of stack levels introduced with FRED architecture. Search for the latest FRED spec in most search engines with this search pattern: site:intel.com FRED (flexible return and event delivery) specification As the native FRED patches are committed in the tip tree "x86/fred" branch: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/?h=x86/fred, and we have received a good amount of review comments for v1, it's time to send out v2 based on this branch for further help from the community. Patch 1-2 are cleanups to VMX basic and misc MSRs, which were sent out earlier as a preparation for FRED changes: https://lore.kernel.org/kvm/20240206182032.1596-1-xin3.li@intel.com/T/#u Patch 3-15 add FRED support to VMX. Patch 16-21 add FRED support to nested VMX. Patch 22 exposes FRED and its baseline features to KVM guests. Patch 23-25 add FRED selftests. There is also a counterpart qemu patch set for FRED at: https://lore.kernel.org/qemu-devel/20231109072012.8078-1-xin3.li@intel.com/…, which works with this patch set to allow KVM to run FRED guests. Changes since v1: * Always load the secondary VM exit controls (Sean Christopherson). * Remove FRED VM entry/exit controls consistency checks in setup_vmcs_config() (Sean Christopherson). * Clear FRED VM entry/exit controls if FRED is not enumerated (Chao Gao). * Use guest_can_use() to trace FRED enumeration in a vcpu (Chao Gao). * Enable FRED MSRs intercept if FRED is no longer enumerated in CPUID (Chao Gao). * Move guest FRED states init into __vmx_vcpu_reset() (Chao Gao). * Don't use guest_cpuid_has() in vmx_prepare_switch_to_{host,guest}(), which are called from IRQ-disabled context (Chao Gao). * Reset msr_guest_fred_rsp0 in __vmx_vcpu_reset() (Chao Gao). * Fail host requested FRED MSRs access if KVM cannot virtualize FRED (Chao Gao). * Handle the case FRED MSRs are valid but KVM cannot virtualize FRED (Chao Gao). * Add sanity checks when writing to FRED MSRs. * Explain why it is ok to only check CR4.FRED in kvm_is_fred_enabled() (Chao Gao). * Document event data should be equal to CR2/DR6/IA32_XFD_ERR instead of using WARN_ON() (Chao Gao). * Zero event data if a #NM was not caused by extended feature disable (Chao Gao). * Set the nested flag when there is an original interrupt (Chao Gao). * Dump guest FRED states only if guest has FRED enabled (Nikolay Borisov). * Add a prerequisite to SHADOW_FIELD_R[OW] macros * Remove hyperv TLFS related changes (Jeremi Piotrowski). * Use kvm_cpu_cap_has() instead of cpu_feature_enabled() to decouple KVM's capability to virtualize a feature and host's enabling of a feature (Chao Gao). Xin Li (25): KVM: VMX: Cleanup VMX basic information defines and usages KVM: VMX: Cleanup VMX misc information defines and usages KVM: VMX: Add support for the secondary VM exit controls KVM: x86: Mark CR4.FRED as not reserved KVM: VMX: Initialize FRED VM entry/exit controls in vmcs_config KVM: VMX: Defer enabling FRED MSRs save/load until after set CPUID KVM: VMX: Set intercept for FRED MSRs KVM: VMX: Initialize VMCS FRED fields KVM: VMX: Switch FRED RSP0 between host and guest KVM: VMX: Add support for FRED context save/restore KVM: x86: Add kvm_is_fred_enabled() KVM: VMX: Handle FRED event data KVM: VMX: Handle VMX nested exception for FRED KVM: VMX: Disable FRED if FRED consistency checks fail KVM: VMX: Dump FRED context in dump_vmcs() KVM: VMX: Invoke vmx_set_cpu_caps() before nested setup KVM: nVMX: Add support for the secondary VM exit controls KVM: nVMX: Add a prerequisite to SHADOW_FIELD_R[OW] macros KVM: nVMX: Add FRED VMCS fields KVM: nVMX: Add support for VMX FRED controls KVM: nVMX: Add VMCS FRED states checking KVM: x86: Allow FRED/LKGS/WRMSRNS to be exposed to guests KVM: selftests: Run debug_regs test with FRED enabled KVM: selftests: Add a new VM guest mode to run user level code KVM: selftests: Add fred exception tests Documentation/virt/kvm/x86/nested-vmx.rst | 19 + arch/x86/include/asm/kvm_host.h | 8 +- arch/x86/include/asm/msr-index.h | 15 +- arch/x86/include/asm/vmx.h | 59 ++- arch/x86/kvm/cpuid.c | 4 +- arch/x86/kvm/governed_features.h | 1 + arch/x86/kvm/kvm_cache_regs.h | 17 + arch/x86/kvm/svm/svm.c | 4 +- arch/x86/kvm/vmx/capabilities.h | 30 +- arch/x86/kvm/vmx/nested.c | 329 ++++++++++++--- arch/x86/kvm/vmx/nested.h | 2 +- arch/x86/kvm/vmx/vmcs.h | 1 + arch/x86/kvm/vmx/vmcs12.c | 19 + arch/x86/kvm/vmx/vmcs12.h | 38 ++ arch/x86/kvm/vmx/vmcs_shadow_fields.h | 80 ++-- arch/x86/kvm/vmx/vmx.c | 385 +++++++++++++++--- arch/x86/kvm/vmx/vmx.h | 15 +- arch/x86/kvm/x86.c | 103 ++++- arch/x86/kvm/x86.h | 5 +- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/kvm_util_base.h | 1 + .../selftests/kvm/include/x86_64/processor.h | 36 ++ tools/testing/selftests/kvm/lib/kvm_util.c | 5 +- .../selftests/kvm/lib/x86_64/processor.c | 15 +- tools/testing/selftests/kvm/lib/x86_64/vmx.c | 4 +- .../testing/selftests/kvm/x86_64/debug_regs.c | 50 ++- .../testing/selftests/kvm/x86_64/fred_test.c | 297 ++++++++++++++ 27 files changed, 1320 insertions(+), 223 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/fred_test.c base-commit: e13841907b8fda0ae0ce1ec03684665f578416a8 -- 2.43.0

2 months, 3 weeks

8
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[PATCH] kunit: tool: Build compile_commands.json

by Brendan Jackman

compile_commands.json is used by clangd[1] to provide code navigation and completion functionality to editors. See [2] for an example configuration that includes this functionality for VSCode. It can currently be built manually when using kunit.py, by running: ./scripts/clang-tools/gen_compile_commands.py -d .kunit With this change however, it's built automatically so you don't need to manually keep it up to date. Unlike the manual approach, having make build the compile_commands.json means that it appears in the build output tree instead of at the root of the source tree, so you'll need to add --compile-commands-dir= to your clangd args for it to be found. [1] https://clangd.llvm.org/ [2] https://github.com/FlorentRevest/linux-kernel-vscode Signed-off-by: Brendan Jackman <jackmanb(a)google.com> --- tools/testing/kunit/kunit_kernel.py | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py index 7254c110ff23..61931c4926fd 100644 --- a/tools/testing/kunit/kunit_kernel.py +++ b/tools/testing/kunit/kunit_kernel.py @@ -72,7 +72,8 @@ class LinuxSourceTreeOperations: raise ConfigError(e.output.decode()) def make(self, jobs: int, build_dir: str, make_options: Optional[List[str]]) -> None: - command = ['make', 'ARCH=' + self._linux_arch, 'O=' + build_dir, '--jobs=' + str(jobs)] + command = ['make', 'all', 'compile_commands.json', 'ARCH=' + self._linux_arch, + 'O=' + build_dir, '--jobs=' + str(jobs)] if make_options: command.extend(make_options) if self._cross_compile: --- base-commit: 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4 change-id: 20240516-kunit-compile-commands-d994074fc2be Best regards, -- Brendan Jackman <jackmanb(a)google.com>

3 months, 1 week

3
2
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[PATCH v3 0/7] iommufd support pasid attach/replace

by Yi Liu

PASID (Process Address Space ID) is a PCIe extension to tag the DMA transactions out of a physical device, and most modern IOMMU hardware have supported PASID granular address translation. So a PASID-capable device can be attached to multiple hwpts (a.k.a. domains), each attachment is tagged with a pasid. This series is based on a preparation series [1], it first adds a missing iommu API to replace domain for a pasid. Based on the iommu pasid attach/ replace/detach APIs, this series adds iommufd APIs for device drivers to attach/replace/detach pasid to/from hwpt per userspace's request, and adds selftest to validate the iommufd APIs. The completed code can be found in below link [2]. Heads up! The existing iommufd selftest was broken, there was a fix [3] to it, but not been upstreamed yet. If want to run the iommufd selftest, please apply that fix. Sorry for the inconvenience. [1] https://lore.kernel.org/linux-iommu/20240628085538.47049-1-yi.l.liu@intel.c… [2] https://github.com/yiliu1765/iommufd/tree/iommufd_pasid [3] https://lore.kernel.org/linux-iommu/20240111073213.180020-1-baolu.lu@linux.… Change log: v3: - Split the set_dev_pasid op enhancements for domain replacement to be a separate series "Make set_dev_pasid op supportting domain replacement" [1]. The below changes are made in the separate series. *) set_dev_pasid() callback should keep the old config if failed to attach to a domain. This simplifies the caller a lot as caller does not need to attach it back to old domain explicitly. This also avoids some corner cases in which the core may do duplicated domain attachment as described in below link (Jason) https://lore.kernel.org/linux-iommu/BN9PR11MB52768C98314A95AFCD2FA6478C0F2@… *) Drop patch 10 of v2 as it's a bug fix and can be submitted separately (Kevin) *) Rebase on top of Baolu's domain_alloc_paging refactor series (Jason) - Drop the attach_data which includes attach_fn and pasid, insteadly passing the pasid through the device attach path. (Jason) - Add a pasid-num-bits property to mock dev to make pasid selftest work (Kevin) v2: https://lore.kernel.org/linux-iommu/20240412081516.31168-1-yi.l.liu@intel.c… - Domain replace for pasid should be handled in set_dev_pasid() callbacks instead of remove_dev_pasid and call set_dev_pasid afteward in iommu layer (Jason) - Make xarray operations more self-contained in iommufd pasid attach/replace/detach (Jason) - Tweak the dev_iommu_get_max_pasids() to allow iommu driver to populate the max_pasids. This makes the iommufd selftest simpler to meet the max_pasids check in iommu_attach_device_pasid() (Jason) v1: https://lore.kernel.org/kvm/20231127063428.127436-1-yi.l.liu@intel.com/#r - Implemnet iommu_replace_device_pasid() to fall back to the original domain if this replacement failed (Kevin) - Add check in do_attach() to check corressponding attach_fn per the pasid value. rfc: https://lore.kernel.org/linux-iommu/20230926092651.17041-1-yi.l.liu@intel.c… Regards, Yi Liu Yi Liu (7): iommu: Introduce a replace API for device pasid iommufd: Pass pasid through the device attach/replace path iommufd: Support attach/replace hwpt per pasid iommufd/selftest: Add set_dev_pasid and remove_dev_pasid in mock iommu iommufd/selftest: Add a helper to get test device iommufd/selftest: Add test ops to test pasid attach/detach iommufd/selftest: Add coverage for iommufd pasid attach/detach drivers/iommu/iommu-priv.h | 3 + drivers/iommu/iommu.c | 80 ++++++- drivers/iommu/iommufd/Makefile | 1 + drivers/iommu/iommufd/device.c | 31 +-- drivers/iommu/iommufd/iommufd_private.h | 15 ++ drivers/iommu/iommufd/iommufd_test.h | 30 +++ drivers/iommu/iommufd/pasid.c | 157 +++++++++++++ drivers/iommu/iommufd/selftest.c | 206 ++++++++++++++++- include/linux/iommufd.h | 6 + tools/testing/selftests/iommu/iommufd.c | 207 ++++++++++++++++++ .../selftests/iommu/iommufd_fail_nth.c | 28 ++- tools/testing/selftests/iommu/iommufd_utils.h | 78 +++++++ 12 files changed, 808 insertions(+), 34 deletions(-) create mode 100644 drivers/iommu/iommufd/pasid.c -- 2.34.1

3 months, 2 weeks

4
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[PATCH] MAINTAINERS: Add selftests/x86 entry

by Muhammad Usama Anjum

There are no maintainers specified for tools/testing/selftests/x86. Shuah has mentioned [1] that the patches should go through x86 tree or in special cases directly to Shuah's tree after getting ack-ed from x86 maintainers. Different people have been confused when sending patches as correct maintainers aren't found by get_maintainer.pl script. Fix this by adding entry to MAINTAINERS file. [1] https://lore.kernel.org/all/90dc0dfc-4c67-4ea1-b705-0585d6e2ec47@linuxfound… Signed-off-by: Muhammad Usama Anjum <usama.anjum(a)collabora.com> --- MAINTAINERS | 1 + 1 file changed, 1 insertion(+) diff --git a/MAINTAINERS b/MAINTAINERS index 523d84b2d6139..f3a17e5d954a3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -24378,6 +24378,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/core F: Documentation/arch/x86/ F: Documentation/devicetree/bindings/x86/ F: arch/x86/ +F: tools/testing/selftests/x86 X86 ENTRY CODE M: Andy Lutomirski <luto(a)kernel.org> -- 2.39.2

3 months, 3 weeks

4
7
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[PATCH RFC 0/3] add support for mm-local memory allocations

by Roman Kagan

In a series posted a few years ago [1], a proposal was put forward to allow the kernel to allocate memory local to a mm and thus push it out of reach for current and future speculation-based cross-process attacks. We still believe this is a nice thing to have. However, in the time passed since that post Linux mm has grown quite a few new goodies, so we'd like to explore possibilities to implement this functionality with less effort and churn leveraging the now available facilities. Specifically, this is a proof-of-concept attempt to implement mm-local allocations piggy-backing on memfd_secret(), using regular user addressess but pinning the pages and flipping the user/supervisor flag on the respective PTEs to make them directly accessible from kernel, and sealing the VMA to prevent userland from taking over the address range. The approach allowed to delegate all the heavy lifting -- address management, interactions with the direct map, cleanup on mm teardown -- to the existing infrastructure, and required zero architecture-specific code. Compared to the approach used in the orignal series, where a dedicated kernel address range and thus a dedicated PGD was used for mm-local allocations, the one proposed here may have certain drawbacks, in particular - using user addresses for kernel memory may violate assumptions in various parts of kernel code which we may not have identified with smoke tests we did - the allocated addresses are guessable by the userland (ATM they are even visible in /proc/PID/maps but that's fixable) which may weaken the security posture Also included is a simple test driver and selftest to smoke test and showcase the feature. The code is PoC RFC and lacks a lot of checks and special case handling, but demonstrates the idea. We'd appreciate any feedback on whether it's a viable approach or it should better be abandoned in favor of the one with dedicated PGD / kernel address range or yet something else. [1] https://lore.kernel.org/lkml/20190612170834.14855-1-mhillenb@amazon.de/ Fares Mehanna (2): mseal: expose interface to seal / unseal user memory ranges mm/secretmem: implement mm-local kernel allocations Roman Kagan (1): drivers/misc: add test driver and selftest for proclocal allocator drivers/misc/Makefile | 1 + tools/testing/selftests/proclocal/Makefile | 6 + include/linux/secretmem.h | 8 + mm/internal.h | 7 + drivers/misc/proclocal-test.c | 200 +++++++++++++++++ mm/gup.c | 4 +- mm/mseal.c | 81 ++++--- mm/secretmem.c | 208 ++++++++++++++++++ .../selftests/proclocal/proclocal-test.c | 150 +++++++++++++ drivers/misc/Kconfig | 15 ++ tools/testing/selftests/proclocal/.gitignore | 1 + 11 files changed, 649 insertions(+), 32 deletions(-) create mode 100644 tools/testing/selftests/proclocal/Makefile create mode 100644 drivers/misc/proclocal-test.c create mode 100644 tools/testing/selftests/proclocal/proclocal-test.c create mode 100644 tools/testing/selftests/proclocal/.gitignore -- 2.34.1 Amazon Web Services Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597

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[PATCH v3 0/3] riscv: mm: Extend mappable memory up to hint address

by Charlie Jenkins

On riscv, mmap currently returns an address from the largest address space that can fit entirely inside of the hint address. This makes it such that the hint address is almost never returned. This patch raises the mappable area up to and including the hint address. This allows mmap to often return the hint address, which allows a performance improvement over searching for a valid address as well as making the behavior more similar to other architectures. Note that a previous patch introduced stronger semantics compared to other architectures for riscv mmap. On riscv, mmap will not use bits in the upper bits of the virtual address depending on the hint address. On other architectures, a random address is returned in the address space requested. On all architectures the hint address will be returned if it is available. This allows riscv applications to configure how many bits in the virtual address should be left empty. This has the two benefits of being able to request address spaces that are smaller than the default and doesn't require the application to know the page table layout of riscv. Signed-off-by: Charlie Jenkins <charlie(a)rivosinc.com> --- Changes in v3: - Add back forgotten semi-colon - Fix test cases - Add support for rv32 - Change cover letter name so it's not the same as patch 1 - Link to v2: https://lore.kernel.org/r/20240130-use_mmap_hint_address-v2-0-f34ebfd33053@… Changes in v2: - Add back forgotten "mmap_end = STACK_TOP_MAX" - Link to v1: https://lore.kernel.org/r/20240129-use_mmap_hint_address-v1-0-4c74da813ba1@… --- Charlie Jenkins (3): riscv: mm: Use hint address in mmap if available selftests: riscv: Generalize mm selftests docs: riscv: Define behavior of mmap Documentation/arch/riscv/vm-layout.rst | 16 ++-- arch/riscv/include/asm/processor.h | 27 +++--- tools/testing/selftests/riscv/mm/mmap_bottomup.c | 23 +---- tools/testing/selftests/riscv/mm/mmap_default.c | 23 +---- tools/testing/selftests/riscv/mm/mmap_test.h | 107 ++++++++++++++--------- 5 files changed, 83 insertions(+), 113 deletions(-) --- base-commit: 556e2d17cae620d549c5474b1ece053430cd50bc change-id: 20240119-use_mmap_hint_address-f9f4b1b6f5f1 -- - Charlie

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Linux-kselftest-mirror June 2024