1. 22 Sep, 2021 22 commits
    • Peter Gonda's avatar
      KVM: SEV: Allow some commands for mirror VM · 5b92b6ca
      Peter Gonda authored
      A mirrored SEV-ES VM will need to call KVM_SEV_LAUNCH_UPDATE_VMSA to
      setup its vCPUs and have them measured, and their VMSAs encrypted. Without
      this change, it is impossible to have mirror VMs as part of SEV-ES VMs.
      
      Also allow the guest status check and debugging commands since they do
      not change any guest state.
      Signed-off-by: default avatarPeter Gonda <pgonda@google.com>
      Cc: Marc Orr <marcorr@google.com>
      Cc: Nathan Tempelman <natet@google.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Sean Christopherson <seanjc@google.com>
      Cc: Steve Rutherford <srutherford@google.com>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: kvm@vger.kernel.org
      Cc: linux-kernel@vger.kernel.org
      Cc: stable@vger.kernel.org
      Fixes: 54526d1f ("KVM: x86: Support KVM VMs sharing SEV context", 2021-04-21)
      Message-Id: <20210921150345.2221634-3-pgonda@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      5b92b6ca
    • Peter Gonda's avatar
      KVM: SEV: Update svm_vm_copy_asid_from for SEV-ES · f43c887c
      Peter Gonda authored
      For mirroring SEV-ES the mirror VM will need more then just the ASID.
      The FD and the handle are required to all the mirror to call psp
      commands. The mirror VM will need to call KVM_SEV_LAUNCH_UPDATE_VMSA to
      setup its vCPUs' VMSAs for SEV-ES.
      Signed-off-by: default avatarPeter Gonda <pgonda@google.com>
      Cc: Marc Orr <marcorr@google.com>
      Cc: Nathan Tempelman <natet@google.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Sean Christopherson <seanjc@google.com>
      Cc: Steve Rutherford <srutherford@google.com>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: kvm@vger.kernel.org
      Cc: linux-kernel@vger.kernel.org
      Cc: stable@vger.kernel.org
      Fixes: 54526d1f ("KVM: x86: Support KVM VMs sharing SEV context", 2021-04-21)
      Message-Id: <20210921150345.2221634-2-pgonda@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f43c887c
    • Chenyi Qiang's avatar
      KVM: nVMX: Fix nested bus lock VM exit · 24a996ad
      Chenyi Qiang authored
      Nested bus lock VM exits are not supported yet. If L2 triggers bus lock
      VM exit, it will be directed to L1 VMM, which would cause unexpected
      behavior. Therefore, handle L2's bus lock VM exits in L0 directly.
      
      Fixes: fe6b6bc8 ("KVM: VMX: Enable bus lock VM exit")
      Signed-off-by: default avatarChenyi Qiang <chenyi.qiang@intel.com>
      Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
      Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
      Message-Id: <20210914095041.29764-1-chenyi.qiang@intel.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      24a996ad
    • Sean Christopherson's avatar
      KVM: x86: Identify vCPU0 by its vcpu_idx instead of its vCPUs array entry · 94c245a2
      Sean Christopherson authored
      Use vcpu_idx to identify vCPU0 when updating HyperV's TSC page, which is
      shared by all vCPUs and "owned" by vCPU0 (because vCPU0 is the only vCPU
      that's guaranteed to exist).  Using kvm_get_vcpu() to find vCPU works,
      but it's a rather odd and suboptimal method to check the index of a given
      vCPU.
      
      No functional change intended.
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Reviewed-by: default avatarJim Mattson <jmattson@google.com>
      Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
      Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
      Message-Id: <20210910183220.2397812-3-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      94c245a2
    • Sean Christopherson's avatar
      KVM: x86: Query vcpu->vcpu_idx directly and drop its accessor · 4eeef242
      Sean Christopherson authored
      Read vcpu->vcpu_idx directly instead of bouncing through the one-line
      wrapper, kvm_vcpu_get_idx(), and drop the wrapper.  The wrapper is a
      remnant of the original implementation and serves no purpose; remove it
      before it gains more users.
      
      Back when kvm_vcpu_get_idx() was added by commit 497d72d8 ("KVM: Add
      kvm_vcpu_get_idx to get vcpu index in kvm->vcpus"), the implementation
      was more than just a simple wrapper as vcpu->vcpu_idx did not exist and
      retrieving the index meant walking over the vCPU array to find the given
      vCPU.
      
      When vcpu_idx was introduced by commit 8750e72a ("KVM: remember
      position in kvm->vcpus array"), the helper was left behind, likely to
      avoid extra thrash (but even then there were only two users, the original
      arm usage having been removed at some point in the past).
      
      No functional change intended.
      Suggested-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
      Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
      Message-Id: <20210910183220.2397812-2-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      4eeef242
    • Hou Wenlong's avatar
      kvm: fix wrong exception emulation in check_rdtsc · e9337c84
      Hou Wenlong authored
      According to Intel's SDM Vol2 and AMD's APM Vol3, when
      CR4.TSD is set, use rdtsc/rdtscp instruction above privilege
      level 0 should trigger a #GP.
      
      Fixes: d7eb8203 ("KVM: SVM: Add intercept checks for remaining group7 instructions")
      Signed-off-by: default avatarHou Wenlong <houwenlong93@linux.alibaba.com>
      Message-Id: <1297c0dd3f1bb47a6d089f850b629c7aa0247040.1629257115.git.houwenlong93@linux.alibaba.com>
      Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
      Reviewed-by: default avatarJim Mattson <jmattson@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e9337c84
    • Sean Christopherson's avatar
      KVM: SEV: Pin guest memory for write for RECEIVE_UPDATE_DATA · 50c03801
      Sean Christopherson authored
      Require the target guest page to be writable when pinning memory for
      RECEIVE_UPDATE_DATA.  Per the SEV API, the PSP writes to guest memory:
      
        The result is then encrypted with GCTX.VEK and written to the memory
        pointed to by GUEST_PADDR field.
      
      Fixes: 15fb7de1 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
      Cc: stable@vger.kernel.org
      Cc: Peter Gonda <pgonda@google.com>
      Cc: Marc Orr <marcorr@google.com>
      Cc: Tom Lendacky <thomas.lendacky@amd.com>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210914210951.2994260-2-seanjc@google.com>
      Reviewed-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
      Reviewed-by: default avatarPeter Gonda <pgonda@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      50c03801
    • Mingwei Zhang's avatar
      KVM: SVM: fix missing sev_decommission in sev_receive_start · f1815e0a
      Mingwei Zhang authored
      DECOMMISSION the current SEV context if binding an ASID fails after
      RECEIVE_START.  Per AMD's SEV API, RECEIVE_START generates a new guest
      context and thus needs to be paired with DECOMMISSION:
      
           The RECEIVE_START command is the only command other than the LAUNCH_START
           command that generates a new guest context and guest handle.
      
      The missing DECOMMISSION can result in subsequent SEV launch failures,
      as the firmware leaks memory and might not able to allocate more SEV
      guest contexts in the future.
      
      Note, LAUNCH_START suffered the same bug, but was previously fixed by
      commit 934002cd ("KVM: SVM: Call SEV Guest Decommission if ASID
      binding fails").
      
      Cc: Alper Gun <alpergun@google.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: David Rienjes <rientjes@google.com>
      Cc: Marc Orr <marcorr@google.com>
      Cc: John Allen <john.allen@amd.com>
      Cc: Peter Gonda <pgonda@google.com>
      Cc: Sean Christopherson <seanjc@google.com>
      Cc: Tom Lendacky <thomas.lendacky@amd.com>
      Cc: Vipin Sharma <vipinsh@google.com>
      Cc: stable@vger.kernel.org
      Reviewed-by: default avatarMarc Orr <marcorr@google.com>
      Acked-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
      Fixes: af43cbbf ("KVM: SVM: Add support for KVM_SEV_RECEIVE_START command")
      Signed-off-by: default avatarMingwei Zhang <mizhang@google.com>
      Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210912181815.3899316-1-mizhang@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f1815e0a
    • Peter Gonda's avatar
      KVM: SEV: Acquire vcpu mutex when updating VMSA · bb18a677
      Peter Gonda authored
      The update-VMSA ioctl touches data stored in struct kvm_vcpu, and
      therefore should not be performed concurrently with any VCPU ioctl
      that might cause KVM or the processor to use the same data.
      
      Adds vcpu mutex guard to the VMSA updating code. Refactors out
      __sev_launch_update_vmsa() function to deal with per vCPU parts
      of sev_launch_update_vmsa().
      
      Fixes: ad73109a ("KVM: SVM: Provide support to launch and run an SEV-ES guest")
      Signed-off-by: default avatarPeter Gonda <pgonda@google.com>
      Cc: Marc Orr <marcorr@google.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Sean Christopherson <seanjc@google.com>
      Cc: Brijesh Singh <brijesh.singh@amd.com>
      Cc: kvm@vger.kernel.org
      Cc: stable@vger.kernel.org
      Cc: linux-kernel@vger.kernel.org
      Message-Id: <20210915171755.3773766-1-pgonda@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      bb18a677
    • Sergey Senozhatsky's avatar
      KVM: do not shrink halt_poll_ns below grow_start · ae232ea4
      Sergey Senozhatsky authored
      grow_halt_poll_ns() ignores values between 0 and
      halt_poll_ns_grow_start (10000 by default). However,
      when we shrink halt_poll_ns we may fall way below
      halt_poll_ns_grow_start and endup with halt_poll_ns
      values that don't make a lot of sense: like 1 or 9,
      or 19.
      
      VCPU1 trace (halt_poll_ns_shrink equals 2):
      
      VCPU1 grow 10000
      VCPU1 shrink 5000
      VCPU1 shrink 2500
      VCPU1 shrink 1250
      VCPU1 shrink 625
      VCPU1 shrink 312
      VCPU1 shrink 156
      VCPU1 shrink 78
      VCPU1 shrink 39
      VCPU1 shrink 19
      VCPU1 shrink 9
      VCPU1 shrink 4
      
      Mirror what grow_halt_poll_ns() does and set halt_poll_ns
      to 0 as soon as new shrink-ed halt_poll_ns value falls
      below halt_poll_ns_grow_start.
      Signed-off-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Message-Id: <20210902031100.252080-1-senozhatsky@chromium.org>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ae232ea4
    • Yu Zhang's avatar
      KVM: nVMX: fix comments of handle_vmon() · ed7023a1
      Yu Zhang authored
      "VMXON pointer" is saved in vmx->nested.vmxon_ptr since
      commit 3573e22c ("KVM: nVMX: additional checks on
      vmxon region"). Also, handle_vmptrld() & handle_vmclear()
      now have logic to check the VMCS pointer against the VMXON
      pointer.
      
      So just remove the obsolete comments of handle_vmon().
      Signed-off-by: default avatarYu Zhang <yu.c.zhang@linux.intel.com>
      Message-Id: <20210908171731.18885-1-yu.c.zhang@linux.intel.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ed7023a1
    • Haimin Zhang's avatar
      KVM: x86: Handle SRCU initialization failure during page track init · eb7511bf
      Haimin Zhang authored
      Check the return of init_srcu_struct(), which can fail due to OOM, when
      initializing the page track mechanism.  Lack of checking leads to a NULL
      pointer deref found by a modified syzkaller.
      Reported-by: default avatarTCS Robot <tcs_robot@tencent.com>
      Signed-off-by: default avatarHaimin Zhang <tcs_kernel@tencent.com>
      Message-Id: <1630636626-12262-1-git-send-email-tcs_kernel@tencent.com>
      [Move the call towards the beginning of kvm_arch_init_vm. - Paolo]
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      eb7511bf
    • Sean Christopherson's avatar
      KVM: VMX: Remove defunct "nr_active_uret_msrs" field · cd36ae87
      Sean Christopherson authored
      Remove vcpu_vmx.nr_active_uret_msrs and its associated comment, which are
      both defunct now that KVM keeps the list constant and instead explicitly
      tracks which entries need to be loaded into hardware.
      
      No functional change intended.
      
      Fixes: ee9d22e0 ("KVM: VMX: Use flag to indicate "active" uret MSRs instead of sorting list")
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210908002401.1947049-1-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      cd36ae87
    • Oliver Upton's avatar
      selftests: KVM: Align SMCCC call with the spec in steal_time · 01f91acb
      Oliver Upton authored
      The SMC64 calling convention passes a function identifier in w0 and its
      parameters in x1-x17. Given this, there are two deviations in the
      SMC64 call performed by the steal_time test: the function identifier is
      assigned to a 64 bit register and the parameter is only 32 bits wide.
      
      Align the call with the SMCCC by using a 32 bit register to handle the
      function identifier and increasing the parameter width to 64 bits.
      Suggested-by: default avatarAndrew Jones <drjones@redhat.com>
      Signed-off-by: default avatarOliver Upton <oupton@google.com>
      Reviewed-by: default avatarAndrew Jones <drjones@redhat.com>
      Message-Id: <20210921171121.2148982-3-oupton@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      01f91acb
    • Oliver Upton's avatar
      selftests: KVM: Fix check for !POLLIN in demand_paging_test · 90b54129
      Oliver Upton authored
      The logical not operator applies only to the left hand side of a bitwise
      operator. As such, the check for POLLIN not being set in revents wrong.
      Fix it by adding parentheses around the bitwise expression.
      
      Fixes: 4f72180e ("KVM: selftests: Add demand paging content to the demand paging test")
      Reviewed-by: default avatarAndrew Jones <drjones@redhat.com>
      Signed-off-by: default avatarOliver Upton <oupton@google.com>
      Message-Id: <20210921171121.2148982-2-oupton@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      90b54129
    • Sean Christopherson's avatar
      KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT · 03a6e840
      Sean Christopherson authored
      Explicitly zero the guest's CR3 and mark it available+dirty at RESET/INIT.
      Per Intel's SDM and AMD's APM, CR3 is zeroed at both RESET and INIT.  For
      RESET, this is a nop as vcpu is zero-allocated.  For INIT, the bug has
      likely escaped notice because no firmware/kernel puts its page tables root
      at PA=0, let alone relies on INIT to get the desired CR3 for such page
      tables.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210921000303.400537-3-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      03a6e840
    • Sean Christopherson's avatar
      KVM: x86: Mark all registers as avail/dirty at vCPU creation · 7117003f
      Sean Christopherson authored
      Mark all registers as available and dirty at vCPU creation, as the vCPU has
      obviously not been loaded into hardware, let alone been given the chance to
      be modified in hardware.  On SVM, reading from "uninitialized" hardware is
      a non-issue as VMCBs are zero allocated (thus not truly uninitialized) and
      hardware does not allow for arbitrary field encoding schemes.
      
      On VMX, backing memory for VMCSes is also zero allocated, but true
      initialization of the VMCS _technically_ requires VMWRITEs, as the VMX
      architectural specification technically allows CPU implementations to
      encode fields with arbitrary schemes.  E.g. a CPU could theoretically store
      the inverted value of every field, which would result in VMREAD to a
      zero-allocated field returns all ones.
      
      In practice, only the AR_BYTES fields are known to be manipulated by
      hardware during VMREAD/VMREAD; no known hardware or VMM (for nested VMX)
      does fancy encoding of cacheable field values (CR0, CR3, CR4, etc...).  In
      other words, this is technically a bug fix, but practically speakings it's
      a glorified nop.
      
      Failure to mark registers as available has been a lurking bug for quite
      some time.  The original register caching supported only GPRs (+RIP, which
      is kinda sorta a GPR), with the masks initialized at ->vcpu_reset().  That
      worked because the two cacheable registers, RIP and RSP, are generally
      speaking not read as side effects in other flows.
      
      Arguably, commit aff48baa ("KVM: Fetch guest cr3 from hardware on
      demand") was the first instance of failure to mark regs available.  While
      _just_ marking CR3 available during vCPU creation wouldn't have fixed the
      VMREAD from an uninitialized VMCS bug because ept_update_paging_mode_cr0()
      unconditionally read vmcs.GUEST_CR3, marking CR3 _and_ intentionally not
      reading GUEST_CR3 when it's available would have avoided VMREAD to a
      technically-uninitialized VMCS.
      
      Fixes: aff48baa ("KVM: Fetch guest cr3 from hardware on demand")
      Fixes: 6de4f3ad ("KVM: Cache pdptrs")
      Fixes: 6de12732 ("KVM: VMX: Optimize vmx_get_rflags()")
      Fixes: 2fb92db1 ("KVM: VMX: Cache vmcs segment fields")
      Fixes: bd31fe49 ("KVM: VMX: Add proper cache tracking for CR0")
      Fixes: f98c1e77 ("KVM: VMX: Add proper cache tracking for CR4")
      Fixes: 5addc235 ("KVM: VMX: Cache vmcs.EXIT_QUALIFICATION using arch avail_reg flags")
      Fixes: 87915858 ("KVM: VMX: Cache vmcs.EXIT_INTR_INFO using arch avail_reg flags")
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210921000303.400537-2-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      7117003f
    • Sean Christopherson's avatar
      KVM: selftests: Remove __NR_userfaultfd syscall fallback · 2da4a235
      Sean Christopherson authored
      Revert the __NR_userfaultfd syscall fallback added for KVM selftests now
      that x86's unistd_{32,63}.h overrides are under uapi/ and thus not in
      KVM selftests' search path, i.e. now that KVM gets x86 syscall numbers
      from the installed kernel headers.
      
      No functional change intended.
      Reviewed-by: default avatarBen Gardon <bgardon@google.com>
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210901203030.1292304-6-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      2da4a235
    • Sean Christopherson's avatar
      KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs · 61e52f16
      Sean Christopherson authored
      Add a test to verify an rseq's CPU ID is updated correctly if the task is
      migrated while the kernel is handling KVM_RUN.  This is a regression test
      for a bug introduced by commit 72c3c0fe ("x86/kvm: Use generic xfer
      to guest work function"), where TIF_NOTIFY_RESUME would be cleared by KVM
      without updating rseq, leading to a stale CPU ID and other badness.
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Message-Id: <20210901203030.1292304-5-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      61e52f16
    • Sean Christopherson's avatar
      tools: Move x86 syscall number fallbacks to .../uapi/ · de5f4213
      Sean Christopherson authored
      Move unistd_{32,64}.h from x86/include/asm to x86/include/uapi/asm so
      that tools/selftests that install kernel headers, e.g. KVM selftests, can
      include non-uapi tools headers, e.g. to get 'struct list_head', without
      effectively overriding the installed non-tool uapi headers.
      
      Swapping KVM's search order, e.g. to search the kernel headers before
      tool headers, is not a viable option as doing results in linux/type.h and
      other core headers getting pulled from the kernel headers, which do not
      have the kernel-internal typedefs that are used through tools, including
      many files outside of selftests/kvm's control.
      
      Prior to commit cec07f53 ("perf tools: Move syscall number fallbacks
      from perf-sys.h to tools/arch/x86/include/asm/"), the handcoded numbers
      were actual fallbacks, i.e. overriding unistd_{32,64}.h from the kernel
      headers was unintentional.
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210901203030.1292304-4-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      de5f4213
    • Sean Christopherson's avatar
      entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() · a68de80f
      Sean Christopherson authored
      Invoke rseq_handle_notify_resume() from tracehook_notify_resume() now
      that the two function are always called back-to-back by architectures
      that have rseq.  The rseq helper is stubbed out for architectures that
      don't support rseq, i.e. this is a nop across the board.
      
      Note, tracehook_notify_resume() is horribly named and arguably does not
      belong in tracehook.h as literally every line of code in it has nothing
      to do with tracing.  But, that's been true since commit a42c6ded
      ("move key_repace_session_keyring() into tracehook_notify_resume()")
      first usurped tracehook_notify_resume() back in 2012.  Punt cleaning that
      mess up to future patches.
      
      No functional change intended.
      Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210901203030.1292304-3-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      a68de80f
    • Sean Christopherson's avatar
      KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guest · 8646e536
      Sean Christopherson authored
      Invoke rseq's NOTIFY_RESUME handler when processing the flag prior to
      transferring to a KVM guest, which is roughly equivalent to an exit to
      userspace and processes many of the same pending actions.  While the task
      cannot be in an rseq critical section as the KVM path is reachable only
      by via ioctl(KVM_RUN), the side effects that apply to rseq outside of a
      critical section still apply, e.g. the current CPU needs to be updated if
      the task is migrated.
      
      Clearing TIF_NOTIFY_RESUME without informing rseq can lead to segfaults
      and other badness in userspace VMMs that use rseq in combination with KVM,
      e.g. due to the CPU ID being stale after task migration.
      
      Fixes: 72c3c0fe ("x86/kvm: Use generic xfer to guest work function")
      Reported-by: default avatarPeter Foley <pefoley@google.com>
      Bisected-by: default avatarDoug Evans <dje@google.com>
      Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Cc: Shakeel Butt <shakeelb@google.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
      Message-Id: <20210901203030.1292304-2-seanjc@google.com>
      Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      8646e536
  2. 20 Sep, 2021 2 commits
    • Linus Torvalds's avatar
      Linux 5.15-rc2 · e4e737bb
      Linus Torvalds authored
      e4e737bb
    • Linus Torvalds's avatar
      pci_iounmap'2: Electric Boogaloo: try to make sense of it all · 316e8d79
      Linus Torvalds authored
      Nathan Chancellor reports that the recent change to pci_iounmap in
      commit 9caea000 ("parisc: Declare pci_iounmap() parisc version only
      when CONFIG_PCI enabled") causes build errors on arm64.
      
      It took me about two hours to convince myself that I think I know what
      the logic of that mess of #ifdef's in the <asm-generic/io.h> header file
      really aim to do, and rewrite it to be easier to follow.
      
      Famous last words.
      
      Anyway, the code has now been lifted from that grotty header file into
      lib/pci_iomap.c, and has fairly extensive comments about what the logic
      is.  It also avoids indirecting through another confusing (and badly
      named) helper function that has other preprocessor config conditionals.
      
      Let's see what odd architecture did something else strange in this area
      to break things.  But my arm64 cross build is clean.
      
      Fixes: 9caea000 ("parisc: Declare pci_iounmap() parisc version only when CONFIG_PCI enabled")
      Reported-by: default avatarNathan Chancellor <nathan@kernel.org>
      Cc: Helge Deller <deller@gmx.de>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Guenter Roeck <linux@roeck-us.net>
      Cc: Ulrich Teichert <krypton@ulrich-teichert.org>
      Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      316e8d79
  3. 19 Sep, 2021 16 commits