On Sunday 13 June 2010 16:26:18 Avi Kivity wrote:
> On 06/11/2010 07:36 AM, Sheng Yang wrote:
> > This patch enable save/restore of xsave state.
> >
> > +static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
> > + struct kvm_xsave *guest_xsave)
> > +{
> > + u64 xstate_bv =
> > + *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)];
> > + int size;
> > +
> > + if (cpu_has_xsave) {
> > + if (xstate_bv& XSTATE_YMM)
> > + size = XSAVE_YMM_OFFSET + XSAVE_YMM_SIZE;
> > + else
> > + size = XSAVE_HDR_OFFSET + XSAVE_HDR_SIZE;
> > + memcpy(&vcpu->arch.guest_fpu.state->xsave,
> > + guest_xsave->region, size);
>
> This allows userspace to overflow host memory by specifying XSTATE_YMM
> on a host that doesn't support it.
>
> Better to just use the host's size of the structure.
Yes, should good enough.
>
> > + } else {
> > + if (xstate_bv& ~XSTATE_FPSSE)
> > + return -EINVAL;
> > + size = sizeof(struct i387_fxsave_struct);
> > + memcpy(&vcpu->arch.guest_fpu.state->fxsave,
> > + guest_xsave->region, size);
> > + }
> > + return 0;
> > +}
> > +
> >
> > +
> > +static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
> > + struct kvm_xcrs *guest_xcrs)
> > +{
> > + int i, r = 0;
> > +
> > + if (!cpu_has_xsave)
> > + return -EINVAL;
>
> Too strict?
For no cpu_has_xsave, the KVM_CAP_XCRS would return 0, so this ioctl shouldn't
be
called.
>
> > +
> > + if (guest_xcrs->nr_xcrs> KVM_MAX_XCRS)
> > + return -EFAULT;
>
> EFAULT is for faults during access to userspace. EINVAL or E2BIG.
>
> Need to ensure flags is 0 for forward compatibility.
OK.
>
> > +
> > + for (i = 0; i< guest_xcrs->nr_xcrs; i++)
> > + /* Only support XCR0 currently */
> > + if (guest_xcrs->xcrs[0].xcr == XCR_XFEATURE_ENABLED_MASK) {
> > + r = __kvm_set_xcr(vcpu, XCR_XFEATURE_ENABLED_MASK,
> > + guest_xcrs->xcrs[0].value);
> > + break;
> > + }
> > + if (r)
> > + r = -EFAULT;
>
> EINVAL
OK
>
> > + return r;
> > +}
> > +
--
regards
Yang, Sheng
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