From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Lai Jiangshan <jiangshanlai@gmail.com>,
Lai Jiangshan <laijs@linux.alibaba.com>
Subject: Re: [PATCH 0/5] KVM: x86: Handle reserved CR4 bit interception in VMX
Date: Mon, 19 Oct 2020 17:59:29 +0200 [thread overview]
Message-ID: <361d91aa-6900-12f3-d5bb-654ab4f9879f@redhat.com> (raw)
In-Reply-To: <20200930041659.28181-1-sean.j.christopherson@intel.com>
On 30/09/20 06:16, Sean Christopherson wrote:
> This series stems from Lai's RFC patches to intercept LA57 and let the
> guest own FSGSBASE[*]. Discussion and inspection revealed that KVM does
> not handle the case where LA57 is supported in hardware but not exposed to
> the guest. This is actually true for all CR4 bits, but LA57 is currently
> the only bit that can be reserved and also owned by the guest. I have
> a unit test for this that I'll post separately.
>
> Intercepting LA57 was by far the easiest fix for the immedidate bug, and
> is likely the right change in the long term as there's no justification
> for letting the guest own LA57.
>
> The middle three patches adjust VMX's CR4 guest/host mask to intercept
> reserved bits. This required reworking CPUID updates to also refresh said
> mask at the correct time.
>
> The last past is Lai's, which let's the guest own FSGSBASE. This depends
> on the reserved bit handling being in place.
>
> Ran everything through unit tests, and ran the kernel's FSGSBASE selftests
> in a VM.
>
> [*] https://lkml.kernel.org/r/20200928083047.3349-1-jiangshanlai@gmail.com
>
> Lai Jiangshan (2):
> KVM: x86: Intercept LA57 to inject #GP fault when it's reserved
> KVM: x86: Let the guest own CR4.FSGSBASE
>
> Sean Christopherson (3):
> KVM: x86: Invoke vendor's vcpu_after_set_cpuid() after all common
> updates
> KVM: x86: Move call to update_exception_bitmap() into VMX code
> KVM: VMX: Intercept guest reserved CR4 bits to inject #GP fault
>
> arch/x86/kvm/cpuid.c | 6 +++---
> arch/x86/kvm/kvm_cache_regs.h | 2 +-
> arch/x86/kvm/vmx/vmx.c | 18 +++++++++++++-----
> 3 files changed, 17 insertions(+), 9 deletions(-)
>
Queued, thanks.
Paolo
next prev parent reply other threads:[~2020-10-19 15:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 4:16 [PATCH 0/5] KVM: x86: Handle reserved CR4 bit interception in VMX Sean Christopherson
2020-09-30 4:16 ` [PATCH 1/5] KVM: x86: Intercept LA57 to inject #GP fault when it's reserved Sean Christopherson
2020-09-30 4:16 ` [PATCH 2/5] KVM: x86: Invoke vendor's vcpu_after_set_cpuid() after all common updates Sean Christopherson
2020-09-30 4:16 ` [PATCH 3/5] KVM: x86: Move call to update_exception_bitmap() into VMX code Sean Christopherson
2020-09-30 4:16 ` [PATCH 4/5] KVM: VMX: Intercept guest reserved CR4 bits to inject #GP fault Sean Christopherson
2020-09-30 4:16 ` [PATCH 5/5] KVM: x86: Let the guest own CR4.FSGSBASE Sean Christopherson
2020-10-19 15:59 ` Paolo Bonzini [this message]
2020-10-20 9:13 ` [PATCH 0/5] KVM: x86: Handle reserved CR4 bit interception in VMX Paolo Bonzini
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