KVM: x86: Unhost the *_CMD MSR mess

[PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Sean Christopherson 2 years, 10 months ago

Revert the FLUSH_L1D enabling, which has multiple fatal bugs, clean up
the existing PRED_CMD handling, and reintroduce FLUSH_L1D virtualization
without inheriting the mistakes made by PRED_CMD.

The last patch hardens SVM against one of the bugs introduced in the
FLUSH_L1D enabling.

I'll post KUT patches tomorrow.  I have the tests written (and they found
bugs in my code, :shocked-pikachu:), just need to write the changelogs.
Wanted to get this out sooner than later as I'm guessing I'm not the only
one whose VMs won't boot on Intel CPUs...

Sean Christopherson (6):
  KVM: x86: Revert MSR_IA32_FLUSH_CMD.FLUSH_L1D enabling
  KVM: VMX: Passthrough MSR_IA32_PRED_CMD based purely on host+guest
    CPUID
  KVM: SVM: Passthrough MSR_IA32_PRED_CMD based purely on host+guest
    CPUID
  KVM: x86: Move MSR_IA32_PRED_CMD WRMSR emulation to common code
  KVM: x86: Virtualize FLUSH_L1D and passthrough MSR_IA32_FLUSH_CMD
  KVM: SVM: Return the local "r" variable from svm_set_msr()

 arch/x86/kvm/svm/svm.c | 51 +++++++++++-----------------------------
 arch/x86/kvm/vmx/vmx.c | 53 +++++++-----------------------------------
 arch/x86/kvm/vmx/vmx.h |  2 +-
 arch/x86/kvm/x86.c     | 23 ++++++++++++++++++
 4 files changed, 46 insertions(+), 83 deletions(-)


base-commit: d8708b80fa0e6e21bc0c9e7276ad0bccef73b6e7
-- 
2.40.0.rc2.332.ga46443480c-goog

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Paolo Bonzini 2 years, 10 months ago

Queued, thanks.

Paolo

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Sean Christopherson 2 years, 10 months ago

On Wed, Apr 12, 2023, Paolo Bonzini wrote:
> Queued, thanks.

Roger that, I'll drop kvm-x86/cmd_msrs.

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Paolo Bonzini 2 years, 10 months ago

On 3/22/23 02:14, Sean Christopherson wrote:
> Revert the FLUSH_L1D enabling, which has multiple fatal bugs, clean up
> the existing PRED_CMD handling, and reintroduce FLUSH_L1D virtualization
> without inheriting the mistakes made by PRED_CMD.
> 
> The last patch hardens SVM against one of the bugs introduced in the
> FLUSH_L1D enabling.
> 
> I'll post KUT patches tomorrow.  I have the tests written (and they found
> bugs in my code, :shocked-pikachu:), just need to write the changelogs.
> Wanted to get this out sooner than later as I'm guessing I'm not the only
> one whose VMs won't boot on Intel CPUs...

Hi Sean,

did you post them?

Paolo

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Sean Christopherson 2 years, 10 months ago

On Mon, Mar 27, 2023, Paolo Bonzini wrote:
> On 3/22/23 02:14, Sean Christopherson wrote:
> > Revert the FLUSH_L1D enabling, which has multiple fatal bugs, clean up
> > the existing PRED_CMD handling, and reintroduce FLUSH_L1D virtualization
> > without inheriting the mistakes made by PRED_CMD.
> > 
> > The last patch hardens SVM against one of the bugs introduced in the
> > FLUSH_L1D enabling.
> > 
> > I'll post KUT patches tomorrow.  I have the tests written (and they found
> > bugs in my code, :shocked-pikachu:), just need to write the changelogs.
> > Wanted to get this out sooner than later as I'm guessing I'm not the only
> > one whose VMs won't boot on Intel CPUs...
> 
> Hi Sean,
> 
> did you post them?

No, I'll get that done today (I pinky swear this time).

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Paolo Bonzini 2 years, 10 months ago

On 3/27/23 17:28, Sean Christopherson wrote:
>> On 3/22/23 02:14, Sean Christopherson wrote:
>>> Revert the FLUSH_L1D enabling, which has multiple fatal bugs, clean up
>>> the existing PRED_CMD handling, and reintroduce FLUSH_L1D virtualization
>>> without inheriting the mistakes made by PRED_CMD.
>>>
>>> The last patch hardens SVM against one of the bugs introduced in the
>>> FLUSH_L1D enabling.
>>>
>>> I'll post KUT patches tomorrow.  I have the tests written (and they found
>>> bugs in my code, :shocked-pikachu:), just need to write the changelogs.
>>> Wanted to get this out sooner than later as I'm guessing I'm not the only
>>> one whose VMs won't boot on Intel CPUs...
>> Hi Sean,
>>
>> did you post them?
> No, I'll get that done today (I pinky swear this time).

Ok, you can also send me a pull request if you prefer (or I can apply 
the patches to kvm/next myself of course).

Paolo

Re: [PATCH 0/6] KVM: x86: Unhost the *_CMD MSR mess

Posted by Sean Christopherson 2 years, 10 months ago

On Tue, 21 Mar 2023 18:14:34 -0700, Sean Christopherson wrote:
> Revert the FLUSH_L1D enabling, which has multiple fatal bugs, clean up
> the existing PRED_CMD handling, and reintroduce FLUSH_L1D virtualization
> without inheriting the mistakes made by PRED_CMD.
> 
> The last patch hardens SVM against one of the bugs introduced in the
> FLUSH_L1D enabling.
> 
> [...]

Applied to a one-off branch, kvm-x86 cmd_msrs, so that I can get this into
kvm-x86 next and onto linux-next asap.  I'll drop the branch if Paolo wants
to do something else, or if there are issues with the series.

[1/6] KVM: x86: Revert MSR_IA32_FLUSH_CMD.FLUSH_L1D enabling
      https://github.com/kvm-x86/linux/commit/e9c126917c09
[2/6] KVM: VMX: Passthrough MSR_IA32_PRED_CMD based purely on host+guest CPUID
      https://github.com/kvm-x86/linux/commit/4f9babd37df0
[3/6] KVM: SVM: Passthrough MSR_IA32_PRED_CMD based purely on host+guest CPUID
      https://github.com/kvm-x86/linux/commit/5ac641dff621
[4/6] KVM: x86: Move MSR_IA32_PRED_CMD WRMSR emulation to common code
      https://github.com/kvm-x86/linux/commit/584aeda90bd9
[5/6] KVM: x86: Virtualize FLUSH_L1D and passthrough MSR_IA32_FLUSH_CMD
      https://github.com/kvm-x86/linux/commit/5bdebd246db5
[6/6] KVM: SVM: Return the local "r" variable from svm_set_msr()
      https://github.com/kvm-x86/linux/commit/8a16ed8c673c

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes