linux-kernel - Re: [PATCH] KVM: x86: Fix load damaged SSEx MXCSR register

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Message-ID: <CANRm+Cz28VrLXvzhwhUmFZLPLsjv0ZrEdJ4nHT0RMg1cjAmdLw@mail.gmail.com>
Date:   Thu, 11 May 2017 08:56:45 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH] KVM: x86: Fix load damaged SSEx MXCSR register

2017-05-10 23:35 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
>
>
> On 10/05/2017 12:19, Wanpeng Li wrote:
>>                * with old userspace.
>>                */
>> -             if (xstate_bv & ~kvm_supported_xcr0())
>> +             if (xstate_bv & ~kvm_supported_xcr0() ||
>> +                     mxcsr & ~vcpu->arch.guest_fpu.state.xsave.i387.mxcsr_mask)
>>                       return -EINVAL;
>>               load_xsave(vcpu, (u8 *)guest_xsave->region);
>>       } else {
>> -             if (xstate_bv & ~XFEATURE_MASK_FPSSE)
>> +             if (xstate_bv & ~XFEATURE_MASK_FPSSE ||
>> +                     mxcsr & ~vcpu->arch.guest_fpu.state.fxsave.mxcsr_mask)
>>                       return -EINVAL;
>>               memcpy(&vcpu->arch.guest_fpu.state.fxsave,
>>                       guest_xsave->region, sizeof(struct fxregs_state));
>
> Hmm, thinking more about it, maybe use mxcsr_feature_mask instead of
> digging into vcpu->arch.guest_fpu?  If you send v2, please remember to

ERROR: "mxcsr_feature_mask" [arch/x86/kvm/kvm.ko] undefined. So we
should dig into vcpu->arch.guest_fpu.

Regards,
Wanpeng Li