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Subject[PATCH v9 05/12] perf/x86/intel/pt: Introduce a new function to get capability of Intel PT
Date
New function pt_cap_decode() will be invoked in KVM to check
if a specific capability is available in KVM guest.
Another function pt_cap_get() can only check the hardware
capabilities but this may different with KVM guest because
some features may not be exposed to guest.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
---
arch/x86/events/intel/pt.c | 10 ++++++++--
arch/x86/include/asm/intel_pt.h | 2 ++
2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index f65f97a..18a2e80 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -76,14 +76,20 @@
PT_CAP(psb_periods, 1, CPUID_EBX, 0xffff0000),
};

-u32 pt_cap_get(enum pt_capabilities cap)
+u32 pt_cap_decode(u32 *caps, enum pt_capabilities cap)
{
struct pt_cap_desc *cd = &pt_caps[cap];
- u32 c = pt_pmu.caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
+ u32 c = caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
unsigned int shift = __ffs(cd->mask);

return (c & cd->mask) >> shift;
}
+EXPORT_SYMBOL_GPL(pt_cap_decode);
+
+u32 pt_cap_get(enum pt_capabilities cap)
+{
+ return pt_cap_decode(pt_pmu.caps, cap);
+}
EXPORT_SYMBOL_GPL(pt_cap_get);

static ssize_t pt_cap_show(struct device *cdev,
diff --git a/arch/x86/include/asm/intel_pt.h b/arch/x86/include/asm/intel_pt.h
index 2de4db0..9c71453 100644
--- a/arch/x86/include/asm/intel_pt.h
+++ b/arch/x86/include/asm/intel_pt.h
@@ -27,9 +27,11 @@ enum pt_capabilities {
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
void cpu_emergency_stop_pt(void);
extern u32 pt_cap_get(enum pt_capabilities cap);
+extern u32 pt_cap_decode(u32 *caps, enum pt_capabilities cap);
#else
static inline void cpu_emergency_stop_pt(void) {}
static inline u32 pt_cap_get(enum pt_capabilities cap) { return 0; }
+static u32 pt_cap_decode(u32 *caps, enum pt_capabilities cap) { return 0; }
#endif

#endif /* _ASM_X86_INTEL_PT_H */
--
1.8.3.1
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