[PATCH 1/3] KVM: x86: Clear XTILE_CFG if XTILE_DATA is clear

[Aaron Lewis <aaronlewis@google.com>]

Be good citizens by clearing both
CPUID.(EAX=0DH,ECX=0):EAX.XTILECFG[bit-17] and
CPUID.(EAX=0DH,ECX=0):EAX.XTILEDATA[bit-18] if they are both not set.
That way userspace or a guest doesn't fail if it attempts to set XCR0
with the user xfeature bits, i.e. EDX:EAX of CPUID.(EAX=0DH,ECX=0).

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 arch/x86/kvm/cpuid.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0b5bf013fcb8e..2d9910847786a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -977,6 +977,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		u64 permitted_xcr0 = kvm_caps.supported_xcr0 & xstate_get_guest_group_perm();
 		u64 permitted_xss = kvm_caps.supported_xss;
 
+		if (!(permitted_xcr0 & XFEATURE_MASK_XTILE_CFG) ||
+		    !(permitted_xcr0 & XFEATURE_MASK_XTILE_DATA))
+			permitted_xcr0 &= ~XFEATURE_MASK_XTILE;
+
 		entry->eax &= permitted_xcr0;
 		entry->ebx = xstate_required_size(permitted_xcr0, false);
 		entry->ecx = entry->ebx;
-- 
2.39.0.314.g84b9a713c41-goog