linux-kernel - Re: [PATCH 0/6] KVM: x86: x2APIC reserved bits/regs fixes

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Date:   Fri, 13 Jan 2023 19:06:01 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marc Orr <marcorr@...gle.com>, Ben Gardon <bgardon@...gle.com>,
        Venkatesh Srinivas <venkateshs@...omium.org>
Subject: Re: [PATCH 0/6] KVM: x86: x2APIC reserved bits/regs fixes

On 1/7/23 02:10, Sean Christopherson wrote:
> Fixes for edge cases where KVM mishandles reserved bits/regs checks when
> the vCPU is in x2APIC mode.
> 
> The first two patches were previously posted[*], but both patches were
> broken (as posted against upstream), hence I took full credit for doing
> the work and changed Marc to a reporter.
> 
> The VMX APICv fixes are for bugs found when writing tests.  *sigh*
> I didn't Cc those to stable as the odds of breaking something when touching
> the MSR bitmaps seemed higher than someone caring about a 10 year old bug.
> 
> AMD x2AVIC support may or may not suffer similar interception bugs, but I
> don't have hardware to test and this already snowballed further than
> expected...
> 
> [*] https://lore.kernel.org/kvm/20220525173933.1611076-1-venkateshs@chromium.org

Looks good; please feel free to start gathering this in your tree for 6.3.

Next week I'll go through Ben's series as well as Aaron's "Clean up the 
supported xfeatures" and others.

Let me know if you would like me to queue anything of these instead, and 
please remember to set up the tree in linux-next. :)

Thanks,

Paolo

> Sean Christopherson (6):
>    KVM: x86: Inject #GP if WRMSR sets reserved bits in APIC Self-IPI
>    KVM: x86: Inject #GP on x2APIC WRMSR that sets reserved bits 63:32
>    KVM: x86: Mark x2APIC DFR reg as non-existent for x2APIC
>    KVM: x86: Split out logic to generate "readable" APIC regs mask to
>      helper
>    KVM: VMX: Always intercept accesses to unsupported "extended" x2APIC
>      regs
>    KVM: VMX: Intercept reads to invalid and write-only x2APIC registers
> 
>   arch/x86/kvm/lapic.c   | 55 ++++++++++++++++++++++++++----------------
>   arch/x86/kvm/lapic.h   |  2 ++
>   arch/x86/kvm/vmx/vmx.c | 40 +++++++++++++++---------------
>   3 files changed, 57 insertions(+), 40 deletions(-)
> 
> 
> base-commit: 91dc252b0dbb6879e4067f614df1e397fec532a1