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Commit df1daba7 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: support XSAVES usage in the host 



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: f31a9f7c
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: stable@vger.kernel.org
Cc: H. Peter Anvin <hpa@linux.intel.com>
Tested-by: default avatarNadav Amit <namit@cs.technion.ac.il>
Reviewed-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ba7b3920

arch/x86/kvm/x86.c

+83 −7
Original line number Diff line number Diff line
@@ -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