Re: [CFT PATCH 0/2] KVM: support XSAVES usage in the host

From: Nadav Amit
Date: Mon Nov 24 2014 - 13:31:46 EST



> On Nov 24, 2014, at 19:53, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
>
>
> On 24/11/2014 16:28, Nadav Amit wrote:
>>
>> Since kvm_load_guest_fpu is called before the guest_fpu is ever stored, there are 2 more problems that currently cause #GP:
>> 1. XCOMP_BV[63] = 0
>> 2. XSTATE_BV sets a bit (including bit 63) that is not set in XCOMP_BV (XCOMP_BV is initialised to zero).
>>
>> [see SDM 13.11 "OPERATION OF XRSTORSâ]
>>
>> Once I initialise XCOMP_BV to (1ull << 63) | XSTATE_BV, the guest runs successfully.
>> I have not checked any other qemu functionality that might be affected by the patch.
>
> I posted patches that assume that QEMU calls KVM_SET_XSAVE early enough.
> If this is not the case, can you cook up and post a patch to
> kvm_arch_vcpu_init that fixes the remaining problem?

Sure. I will try to do so tomorrow.

Nadav

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