kernel.git/arch/x86/kernel/process.c, branch linux-5.18.y

x86: Handle idle=nomwait cmdline properly for x86_idle

2022-08-17T12:40:20Z

[ Upstream commit 8bcedb4ce04750e1ccc9a6b6433387f6a9166a56 ] When kernel is booted with idle=nomwait do not use MWAIT as the default idle state. If the user boots the kernel with idle=nomwait, it is a clear direction to not use mwait as the default idle state. However, the current code does not take this into consideration while selecting the default idle state on x86. Fix it by checking for the idle=nomwait boot option in prefer_mwait_c1_over_halt(). Also update the documentation around idle=nomwait appropriately. [ dhansen: tweak commit message ] Signed-off-by: Wyes Karny Signed-off-by: Dave Hansen Tested-by: Zhang Rui Link: https://lkml.kernel.org/r/fdc2dc2d0a1bc21c2f53d989ea2d2ee3ccbc0dbe.1654538381.git-series.wyes.karny@amd.com Signed-off-by: Sasha Levin

x86/bugs: Optimize SPEC_CTRL MSR writes

2022-07-23T10:56:48Z

commit c779bc1a9002fa474175b80e72b85c9bf628abb0 upstream. When changing SPEC_CTRL for user control, the WRMSR can be delayed until return-to-user when KERNEL_IBRS has been enabled. This avoids an MSR write during context switch. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman

x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value

2022-07-23T10:56:48Z

commit caa0ff24d5d0e02abce5e65c3d2b7f20a6617be5 upstream. Due to TIF_SSBD and TIF_SPEC_IB the actual IA32_SPEC_CTRL value can differ from x86_spec_ctrl_base. As such, keep a per-CPU value reflecting the current task's MSR content. [jpoimboe: rename] Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Greg Kroah-Hartman

Merge branch 'x86/cpu' into x86/core, to resolve conflicts

2022-03-15T11:52:51Z

Conflicts: arch/x86/include/asm/cpufeatures.h Signed-off-by: Ingo Molnar

x86: Mark stop_this_cpu() __noreturn

2022-03-15T09:32:43Z

vmlinux.o: warning: objtool: smp_stop_nmi_callback()+0x2b: unreachable instruction 0000 0000000000047cf0 : ... 0026 47d16: e8 00 00 00 00 call 47d1b 47d17: R_X86_64_PLT32 stop_this_cpu-0x4 002b 47d1b: b8 01 00 00 00 mov $0x1,%eax Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220308154319.290905453@infradead.org

x86/cpu: Clear SME feature flag when not in use

2022-02-16T18:45:53Z

Currently, the SME CPU feature flag is reflective of whether the CPU supports the feature but not whether it has been activated by the kernel. Change this around to clear the SME feature flag if the kernel is not using it so userspace can determine if it is available and in use from /proc/cpuinfo. As the feature flag is cleared on systems where SME isn't active, use CPUID 0x8000001f to confirm SME availability before calling native_wbinvd(). Signed-off-by: Mario Limonciello Signed-off-by: Borislav Petkov Acked-by: Tom Lendacky Link: https://lore.kernel.org/r/20220216034446.2430634-1-mario.limonciello@amd.com

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2022-01-16T14:15:14Z

Pull kvm updates from Paolo Bonzini: "RISCV: - Use common KVM implementation of MMU memory caches - SBI v0.2 support for Guest - Initial KVM selftests support - Fix to avoid spurious virtual interrupts after clearing hideleg CSR - Update email address for Anup and Atish ARM: - Simplification of the 'vcpu first run' by integrating it into KVM's 'pid change' flow - Refactoring of the FP and SVE state tracking, also leading to a simpler state and less shared data between EL1 and EL2 in the nVHE case - Tidy up the header file usage for the nvhe hyp object - New HYP unsharing mechanism, finally allowing pages to be unmapped from the Stage-1 EL2 page-tables - Various pKVM cleanups around refcounting and sharing - A couple of vgic fixes for bugs that would trigger once the vcpu xarray rework is merged, but not sooner - Add minimal support for ARMv8.7's PMU extension - Rework kvm_pgtable initialisation ahead of the NV work - New selftest for IRQ injection - Teach selftests about the lack of default IPA space and page sizes - Expand sysreg selftest to deal with Pointer Authentication - The usual bunch of cleanups and doc update s390: - fix sigp sense/start/stop/inconsistency - cleanups x86: - Clean up some function prototypes more - improved gfn_to_pfn_cache with proper invalidation, used by Xen emulation - add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery - completely remove potential TOC/TOU races in nested SVM consistency checks - update some PMCs on emulated instructions - Intel AMX support (joint work between Thomas and Intel) - large MMU cleanups - module parameter to disable PMU virtualization - cleanup register cache - first part of halt handling cleanups - Hyper-V enlightened MSR bitmap support for nested hypervisors Generic: - clean up Makefiles - introduce CONFIG_HAVE_KVM_DIRTY_RING - optimize memslot lookup using a tree - optimize vCPU array usage by converting to xarray" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (268 commits) x86/fpu: Fix inline prefix warnings selftest: kvm: Add amx selftest selftest: kvm: Move struct kvm_x86_state to header selftest: kvm: Reorder vcpu_load_state steps for AMX kvm: x86: Disable interception for IA32_XFD on demand x86/fpu: Provide fpu_sync_guest_vmexit_xfd_state() kvm: selftests: Add support for KVM_CAP_XSAVE2 kvm: x86: Add support for getting/setting expanded xstate buffer x86/fpu: Add uabi_size to guest_fpu kvm: x86: Add CPUID support for Intel AMX kvm: x86: Add XCR0 support for Intel AMX kvm: x86: Disable RDMSR interception of IA32_XFD_ERR kvm: x86: Emulate IA32_XFD_ERR for guest kvm: x86: Intercept #NM for saving IA32_XFD_ERR x86/fpu: Prepare xfd_err in struct fpu_guest kvm: x86: Add emulation for IA32_XFD x86/fpu: Provide fpu_update_guest_xfd() for IA32_XFD emulation kvm: x86: Enable dynamic xfeatures at KVM_SET_CPUID2 x86/fpu: Provide fpu_enable_guest_xfd_features() for KVM x86/fpu: Add guest support to xfd_enable_feature() ...

x86/fpu: Extend fpu_xstate_prctl() with guest permissions

2022-01-07T18:33:03Z

KVM requires a clear separation of host user space and guest permissions for dynamic XSTATE components. Add a guest permissions member to struct fpu and a separate set of prctl() arguments: ARCH_GET_XCOMP_GUEST_PERM and ARCH_REQ_XCOMP_GUEST_PERM. The semantics are equivalent to the host user space permission control except for the following constraints: 1) Permissions have to be requested before the first vCPU is created 2) Permissions are frozen when the first vCPU is created to ensure consistency. Any attempt to expand permissions via the prctl() after that point is rejected. Signed-off-by: Thomas Gleixner Signed-off-by: Jing Liu Signed-off-by: Yang Zhong Message-Id: <20220105123532.12586-2-yang.zhong@intel.com> Signed-off-by: Paolo Bonzini

x86: Snapshot thread flags

2021-11-30T23:06:43Z

Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race. To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not. Convert them all to the new flag accessor helpers. Signed-off-by: Mark Rutland Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Acked-by: Paul E. McKenney Link: https://lore.kernel.org/r/20211129130653.2037928-12-mark.rutland@arm.com

x86: Pin task-stack in __get_wchan()

2021-11-19T18:14:57Z

When commit 5d1ceb3969b6 ("x86: Fix __get_wchan() for !STACKTRACE") moved from stacktrace to native unwind_*() usage, the try_get_task_stack() got lost, leading to use-after-free issues for dying tasks. Signed-off-by: Peter Zijlstra (Intel) Fixes: 5d1ceb3969b6 ("x86: Fix __get_wchan() for !STACKTRACE") Link: https://bugzilla.kernel.org/show_bug.cgi?id=215031 Link: https://lore.kernel.org/stable/YZV02RCRVHIa144u@fedora64.linuxtx.org/ Reported-by: Justin Forbes Reported-by: Holger Hoffstätte Cc: Qi Zheng Cc: Kees Cook Cc: Thomas Gleixner Signed-off-by: Linus Torvalds