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[kvm-unit-test,1/3] nVMX: fixed-function performance counters could be not contiguous

Message ID 20241118225207.16596-1-zide.chen@intel.com (mailing list archive)
State New
Headers show
Series [kvm-unit-test,1/3] nVMX: fixed-function performance counters could be not contiguous | expand

Commit Message

Zide Chen Nov. 18, 2024, 10:52 p.m. UTC 
The fixed counters may not be contiguous.  Intel SDM recommends how to
use CPUID.0AH to determine if a Fixed Counter is supported:
	FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i);

For example, it's perfectly valid to have CPUID.0AH.EDX[4:0] == 3 and
CPUID.0AH.ECX == 0x77, but checking the fixed counter index against
CPUID.0AH.EDX[4:0] only, will deem that FxCtr[6:4] are not supported.

Additionally, according to the latest Intel SDM, changed the definition
of cpuidA_edx and renamed num_counters_fixed to num_contiguous_fixed.

Signed-off-by: Zide Chen <zide.chen@intel.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
---
 x86/vmx_tests.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index ffe7064c9221..5261927ad2a4 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -7332,11 +7332,17 @@  union cpuidA_eax {
 	unsigned int full;
 };
 
+union cpuidA_ecx {
+	unsigned int fixed_mask;
+};
+
 union cpuidA_edx {
 	struct {
-		unsigned int num_counters_fixed:5;
+		unsigned int num_contiguous_fixed:5;
 		unsigned int bit_width_fixed:8;
-		unsigned int reserved:9;
+		unsigned int reserved1:2;
+		unsigned int anythread_deprecated:1;
+		unsigned int reserved2:16;
 	} split;
 	unsigned int full;
 };
@@ -7345,14 +7351,19 @@  static bool valid_pgc(u64 val)
 {
 	struct cpuid id;
 	union cpuidA_eax eax;
+	union cpuidA_ecx ecx;
 	union cpuidA_edx edx;
 	u64 mask;
 
 	id = cpuid(0xA);
 	eax.full = id.a;
+	ecx.fixed_mask = id.c;
 	edx.full = id.d;
+
+	/* FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i); */
 	mask = ~(((1ull << eax.split.num_counters_gp) - 1) |
-		 (((1ull << edx.split.num_counters_fixed) - 1) << 32));
+		 (((1ull << edx.split.num_contiguous_fixed) - 1) << 32) |
+		 ((u64)ecx.fixed_mask << 32));
 
 	return !(val & mask);
 }