[PATCH v2 2/4] kvm: cpuid: fix the size of xsaves area

[Wanpeng Li <wanpeng.li@linux.intel.com>]

The section of CPUID(EAX=0xd, ECX=1) in the spec which commit
f5c2290cd01e (KVM: cpuid: mask more bits in leaf 0xd and subleaves)
mentioned is older than SDM.

EBX: Bits 31-00: The size in bytes of the XSAVE area containing all
states enabled by XCR0|IA32_XSS.

The the value of EBX should represent the size of XCR0 related XSAVE
area since IA32_XSS is not used currently.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
v1 -> v2:
 * add F(XSAVEC) check

 arch/x86/kvm/cpuid.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 646e6e8..5b78e9b 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -477,7 +477,10 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 			do_cpuid_1_ent(&entry[i], function, idx);
 			if (idx == 1) {
 				entry[i].eax &= kvm_supported_word10_x86_features;
-				entry[i].ebx = 0;
+				if (entry[i].eax & (F(XSAVES) | F(XSAVEC)))
+					entry[i].ebx = xstate_required_size(supported, true);
+				else
+					entry[i].ebx = xstate_required_size(supported, false);
 			} else {
 				if (entry[i].eax == 0 || !(supported & mask))
 					continue;
-- 
1.9.1