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x86/kvm: Avoid looking up PKRU in XSAVE buffer

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PKRU is being removed from the kernel XSAVE/FPU buffers.  This removal
will probably include warnings for code that look up PKRU in those
buffers.

KVM currently looks up the location of PKRU but doesn't even use the
pointer that it gets back.  Rework the code to avoid calling
get_xsave_addr() except in cases where its result is actually used.

This makes the code more clear and also avoids the inevitable PKRU
warnings.

This is probably a good cleanup and could go upstream idependently
of any PKRU rework.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.541037562@linutronix.de
This commit is contained in:
Dave Hansen 2021-06-23 14:01:49 +02:00 committed by Borislav Petkov
parent 02b93c0b00
commit 71ef453355
1 changed files with 22 additions and 19 deletions
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41
arch/x86/kvm/x86.c
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@ -4604,20 +4604,21 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
*/
valid = xstate_bv & ~XFEATURE_MASK_FPSSE;
while (valid) {
u32 size, offset, ecx, edx;
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
void *src = get_xsave_addr(xsave, xfeature_nr);
void *src;
if (src) {
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, xfeature_nr,
&size, &offset, &ecx, &edx);
if (xfeature_nr == XFEATURE_PKRU)
memcpy(dest + offset, &vcpu->arch.pkru,
sizeof(vcpu->arch.pkru));
else
cpuid_count(XSTATE_CPUID, xfeature_nr,
&size, &offset, &ecx, &edx);
if (xfeature_nr == XFEATURE_PKRU) {
memcpy(dest + offset, &vcpu->arch.pkru,
sizeof(vcpu->arch.pkru));
} else {
src = get_xsave_addr(xsave, xfeature_nr);
if (src)
memcpy(dest + offset, src, size);
}
valid -= xfeature_mask;
@ -4647,18 +4648,20 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
*/
valid = xstate_bv & ~XFEATURE_MASK_FPSSE;
while (valid) {
u32 size, offset, ecx, edx;
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
void *dest = get_xsave_addr(xsave, xfeature_nr);
if (dest) {
u32 size, offset, ecx, edx;
cpuid_count(XSTATE_CPUID, xfeature_nr,
&size, &offset, &ecx, &edx);
if (xfeature_nr == XFEATURE_PKRU)
memcpy(&vcpu->arch.pkru, src + offset,
sizeof(vcpu->arch.pkru));
else
cpuid_count(XSTATE_CPUID, xfeature_nr,
&size, &offset, &ecx, &edx);
if (xfeature_nr == XFEATURE_PKRU) {
memcpy(&vcpu->arch.pkru, src + offset,
sizeof(vcpu->arch.pkru));
} else {
void *dest = get_xsave_addr(xsave, xfeature_nr);
if (dest)
memcpy(dest, src + offset, size);
}