linux-kernel - Re: [GIT PULL] KVM: x86: Fixes for 6.15-rcN

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Message-ID: <CABgObfbKCRggZm7kbeVkAykxO1tEi1v7q=emcSxWWgMLX20WPA@mail.gmail.com>
Date: Sun, 11 May 2025 13:13:33 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] KVM: x86: Fixes for 6.15-rcN

On Fri, May 9, 2025 at 9:01 PM Sean Christopherson <seanjc@...gle.com> wrote:
> Please pull a random variety of fixes for 6.15.  The SRSO change is the
> most urgent fix, everything else has either existed for some time, or isn't
> actively causing problems.

Cool, thanks; pulled.

Paolo

> The following changes since commit 2d7124941a273c7233849a7a2bbfbeb7e28f1caa:
>
>   Merge tag 'kvmarm-fixes-6.15-2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD (2025-04-24 13:28:53 -0400)
>
> are available in the Git repository at:
>
>   https://github.com/kvm-x86/linux.git tags/kvm-x86-fixes-6.15-rcN
>
> for you to fetch changes up to e3417ab75ab2e7dca6372a1bfa26b1be3ac5889e:
>
>   KVM: SVM: Set/clear SRSO's BP_SPEC_REDUCE on 0 <=> 1 VM count transitions (2025-05-08 07:17:10 -0700)
>
> ----------------------------------------------------------------
> KVM x86 fixes for 6.15-rcN
>
>  - Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid causing
>    problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to sanitize the
>    VMCB as its state is undefined after SHUTDOWN, emulating INIT is the
>    least awful choice).
>
>  - Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
>    KVM doesn't goof a sanity check in the future.
>
>  - Free obsolete roots when (re)loading the MMU to fix a bug where
>    pre-faulting memory can get stuck due to always encountering a stale
>    root.
>
>  - When dumping GHCB state, use KVM's snapshot instead of the raw GHCB page
>    to print state, so that KVM doesn't print stale/wrong information.
>
>  - When changing memory attributes (e.g. shared <=> private), add potential
>    hugepage ranges to the mmu_invalidate_range_{start,end} set so that KVM
>    doesn't create a shared/private hugepage when the the corresponding
>    attributes will become mixed (the attributes are commited *after* KVM
>    finishes the invalidation).
>
>  - Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM has at
>    least one active VM.  Effectively BP_SPEC_REDUCE when KVM is loaded led
>    to very measurable performance regressions for non-KVM workloads.
>
> ----------------------------------------------------------------
> Dan Carpenter (1):
>       KVM: x86: Check that the high 32bits are clear in kvm_arch_vcpu_ioctl_run()
>
> Mikhail Lobanov (1):
>       KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
>
> Sean Christopherson (2):
>       KVM: x86/mmu: Prevent installing hugepages when mem attributes are changing
>       KVM: SVM: Set/clear SRSO's BP_SPEC_REDUCE on 0 <=> 1 VM count transitions
>
> Tom Lendacky (1):
>       KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields
>
> Yan Zhao (1):
>       KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload()
>
>  arch/x86/kvm/mmu.h     |  3 ++
>  arch/x86/kvm/mmu/mmu.c | 70 +++++++++++++++++++++++++++++++++++-----------
>  arch/x86/kvm/smm.c     |  1 +
>  arch/x86/kvm/svm/sev.c | 32 ++++++++++++---------
>  arch/x86/kvm/svm/svm.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++----
>  arch/x86/kvm/svm/svm.h |  2 ++
>  arch/x86/kvm/x86.c     |  4 +--
>  7 files changed, 150 insertions(+), 37 deletions(-)
>