On 11/21/2014 10:31 AM, Paolo Bonzini wrote: > Userspace is expecting non-compacted format for KVM_GET_XSAVE, but > struct xsave_struct might be using the compacted format. Convert > in order to preserve userspace ABI. > > Fixes: f31a9f7c71691569359fa7fb8b0acaa44bce0324 > Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Cc: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 48 +++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 43 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 5337039427c8..7e8a20e5615a 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3131,15 +3131,53 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu, > return 0; > } > > +#define XSTATE_COMPACTION_ENABLED (1ULL << 63) > + > +static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu) > +{ > + struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave; > + u64 xstate_bv = vcpu->arch.guest_supported_xcr0 | XSTATE_FPSSE; > + u64 valid; > + > + /* > + * Copy legacy XSAVE area, to avoid complications with CPUID > + * leaves 0 and 1 in the loop below. > + */ > + memcpy(dest, xsave, XSAVE_HDR_OFFSET); > + > + /* Set XSTATE_BV */ > + *(u64 *)(dest + XSAVE_HDR_OFFSET) = xstate_bv; > + > + /* > + * Copy each region from the possibly compacted offset to the > + * non-compacted offset. > + */ > + valid = xstate_bv & ~XSTATE_FPSSE; > + if (xsave->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED) > + valid &= xsave->xsave_hdr.xcomp_bv; > + > + while (valid) { > + u64 feature = valid & -valid; > + int index = fls64(feature) - 1; > + void *src = get_xsave_addr(xsave, feature); > + > + if (src) { > + u32 size, offset, ecx, edx; > + cpuid_count(XSTATE_CPUID, index, > + &size, &offset, &ecx, &edx); > + memcpy(dest + offset, src, size); Is this really the best way to do this? cpuid is serializing, so this is possibly *very* slow. --Andy -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html