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Subject[PATCH v2] KVM: x86: Add Intel CPUID.1F cpuid emulation support
Date
Some new systems have multiple software-visible die within each package.
Add support to expose Intel V2 Extended Topology Enumeration Leaf CPUID.1F.

Co-developed-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
---

==changelog==
v2:
- Apply cpuid.1f check rule on Intel SDM page 3-222 Vol.2A
- Add comment to handle 0x1f anf 0xb in common code
- Reduce check time in a descending-break style

v1: https://lkml.org/lkml/2019/4/22/28

arch/x86/kvm/cpuid.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index fd39516..f9b529e 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -425,6 +425,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

switch (function) {
case 0:
+ /* Check if the cpuid leaf 0x1f is actually implemented */
+ if (entry->eax >= 0x1f && (cpuid_ebx(0x1f) & 0x0000ffff)) {
+ entry->eax = 0x1f;
+ break;
+ }
entry->eax = min(entry->eax, (u32)(f_intel_pt ? 0x14 : 0xd));
break;
case 1:
@@ -544,7 +549,12 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
entry->edx = edx.full;
break;
}
- /* function 0xb has additional index. */
+ /*
+ * Intel documentation states that 0x1f and 0xb have
+ * identical formats and thus can be handled by common code.
+ * (Intel SDM Vol. 2A - Instruction Set Reference - CPUID)
+ */
+ case 0x1f:
case 0xb: {
int i, level_type;

--
1.8.3.1
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