linux-kernel - Re: [PATCH 0/9] KVM: x86: Add a quirk for feature MSR initialization

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Message-ID: <ZyUqtis_QI_otazX@google.com>
Date: Fri, 1 Nov 2024 12:23:34 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/9] KVM: x86: Add a quirk for feature MSR initialization

On Thu, Oct 31, 2024, Sean Christopherson wrote:
> On Fri, 02 Aug 2024 11:55:02 -0700, Sean Christopherson wrote:
> > The primary goal of this series to fix an issue where KVM's initialization
> > of feature MSRs during vCPU creation results in a failed save/restore of
> > PERF_CAPABILITIES.  If userspace configures the VM to _not_ have a PMU,
> > because KVM initializes the vCPU's PERF_CAPABILTIIES, trying to save/restore
> > the non-zero value will be rejected by the destination.
> > 
> > The secondary goal is to try and avoid such goofs in the future, by making
> > it explicitly clear that userspace owns the vCPU model.
> > 
> > [...]
> 
> Applied to kvm-x86 misc, thanks!
> 
> [1/9] KVM: x86: Co-locate initialization of feature MSRs in kvm_arch_vcpu_create()
>       https://github.com/kvm-x86/linux/commit/383383cfd202
> [2/9] KVM: x86: Disallow changing MSR_PLATFORM_INFO after vCPU has run
>       https://github.com/kvm-x86/linux/commit/d76a5e78f16d
> [3/9] KVM: x86: Quirk initialization of feature MSRs to KVM's max configuration
>       https://github.com/kvm-x86/linux/commit/088b8eeb25ec
> [4/9] KVM: x86: Reject userspace attempts to access PERF_CAPABILITIES w/o PDCM
>       https://github.com/kvm-x86/linux/commit/c2eb2d0318c0
> [5/9] KVM: VMX: Remove restriction that PMU version > 0 for PERF_CAPABILITIES
>       https://github.com/kvm-x86/linux/commit/bae593b20e92
> [6/9] KVM: x86: Reject userspace attempts to access ARCH_CAPABILITIES w/o support
>       https://github.com/kvm-x86/linux/commit/83a5fe6cf1eb
> [7/9] KVM: x86: Remove ordering check b/w MSR_PLATFORM_INFO and MISC_FEATURES_ENABLES
>       https://github.com/kvm-x86/linux/commit/9d2dcfb82db1
> [8/9] KVM: selftests: Verify get/set PERF_CAPABILITIES w/o guest PDMC behavior
>       https://github.com/kvm-x86/linux/commit/6a4511f8602f
> [9/9] KVM: selftests: Add a testcase for disabling feature MSRs init quirk
>       https://github.com/kvm-x86/linux/commit/58a7368f104d

FYI, I rebased misc to v6.12-rc5, as patches in another series had already been
taken through the tip tree.  New hashes:

[1/9] KVM: x86: Co-locate initialization of feature MSRs in kvm_arch_vcpu_create()
      https://github.com/kvm-x86/linux/commit/2142ac663a6a
[2/9] KVM: x86: Disallow changing MSR_PLATFORM_INFO after vCPU has run
      https://github.com/kvm-x86/linux/commit/bc2ca3680b30
[3/9] KVM: x86: Quirk initialization of feature MSRs to KVM's max configuration
      https://github.com/kvm-x86/linux/commit/dcb988cdac85
[4/9] KVM: x86: Reject userspace attempts to access PERF_CAPABILITIES w/o PDCM
      https://github.com/kvm-x86/linux/commit/d75cac366f44
[5/9] KVM: VMX: Remove restriction that PMU version > 0 for PERF_CAPABILITIES
      https://github.com/kvm-x86/linux/commit/a1039111192b
[6/9] KVM: x86: Reject userspace attempts to access ARCH_CAPABILITIES w/o support
      https://github.com/kvm-x86/linux/commit/a5d563890b8f
[7/9] KVM: x86: Remove ordering check b/w MSR_PLATFORM_INFO and MISC_FEATURES_ENABLES
      https://github.com/kvm-x86/linux/commit/1ded7a57b805
[8/9] KVM: selftests: Verify get/set PERF_CAPABILITIES w/o guest PDMC behavior
      https://github.com/kvm-x86/linux/commit/b799e3e7da2c
[9/9] KVM: selftests: Add a testcase for disabling feature MSRs init quirk
      https://github.com/kvm-x86/linux/commit/0581dfbad954