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. Likewise, userspace is passing non-compacted format for KVM_SET_XSAVE but the kernel will pass it to XRSTORS, and we need to convert back. Fixes: f31a9f7c71691569359fa7fb8b0acaa44bce0324 Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Reported-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> Tested-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> --- arch/x86/kvm/x86.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 83 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 08b5657e57ed..c259814200bd 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3132,15 +3132,89 @@ 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 = xsave->xsave_hdr.xstate_bv; + 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; + 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); + } + + valid -= feature; + } +} + +static void load_xsave(struct kvm_vcpu *vcpu, u8 *src) +{ + struct xsave_struct *xsave = &vcpu->arch.guest_fpu.state->xsave; + u64 xstate_bv = *(u64 *)(src + XSAVE_HDR_OFFSET); + u64 valid; + + /* + * Copy legacy XSAVE area, to avoid complications with CPUID + * leaves 0 and 1 in the loop below. + */ + memcpy(xsave, src, XSAVE_HDR_OFFSET); + + /* Set XSTATE_BV and possibly XCOMP_BV. */ + xsave->xsave_hdr.xstate_bv = xstate_bv; + if (cpu_has_xsaves) + xsave->xsave_hdr.xcomp_bv = host_xcr0 | XSTATE_COMPACTION_ENABLED; + + /* + * Copy each region from the non-compacted offset to the + * possibly compacted offset. + */ + valid = xstate_bv & ~XSTATE_FPSSE; + while (valid) { + u64 feature = valid & -valid; + int index = fls64(feature) - 1; + void *dest = get_xsave_addr(xsave, feature); + + if (dest) { + u32 size, offset, ecx, edx; + cpuid_count(XSTATE_CPUID, index, + &size, &offset, &ecx, &edx); + memcpy(dest, src + offset, size); + } else + WARN_ON_ONCE(1); + + valid -= feature; + } +} + static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu, struct kvm_xsave *guest_xsave) { if (cpu_has_xsave) { - memcpy(guest_xsave->region, - &vcpu->arch.guest_fpu.state->xsave, - vcpu->arch.guest_xstate_size); - *(u64 *)&guest_xsave->region[XSAVE_HDR_OFFSET / sizeof(u32)] &= - vcpu->arch.guest_supported_xcr0 | XSTATE_FPSSE; + memset(guest_xsave, 0, sizeof(struct kvm_xsave)); + fill_xsave((u8 *) guest_xsave->region, vcpu); } else { memcpy(guest_xsave->region, &vcpu->arch.guest_fpu.state->fxsave, @@ -3164,8 +3238,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu, */ if (xstate_bv & ~kvm_supported_xcr0()) return -EINVAL; - memcpy(&vcpu->arch.guest_fpu.state->xsave, - guest_xsave->region, vcpu->arch.guest_xstate_size); + load_xsave(vcpu, (u8 *)guest_xsave->region); } else { if (xstate_bv & ~XSTATE_FPSSE) return -EINVAL; @@ -6882,6 +6955,9 @@ int fx_init(struct kvm_vcpu *vcpu) return err; fpu_finit(&vcpu->arch.guest_fpu); + if (cpu_has_xsaves) + vcpu->arch.guest_fpu.state->xsave.xsave_hdr.xcomp_bv = + host_xcr0 | XSTATE_COMPACTION_ENABLED; /* * Ensure guest xcr0 is valid for loading -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html