On 8/3/2022 8:36 am, Jim Mattson wrote:
On Wed, Mar 2, 2022 at 3:14 AM Like Xu <like.xu.linux@xxxxxxxxx> wrote:
From: Like Xu <likexu@xxxxxxxxxxx>
The code sketch for reprogram_{gp, fixed}_counter() is similar, while the
fixed counter using the PERF_TYPE_HARDWAR type and the gp being
able to use either PERF_TYPE_HARDWAR or PERF_TYPE_RAW type
depending on the pmc->eventsel value.
After 'commit 761875634a5e ("KVM: x86/pmu: Setup pmc->eventsel
for fixed PMCs")', the pmc->eventsel of the fixed counter will also have
been setup with the same semantic value and will not be changed during
the guest runtime. But essentially, "the HARDWARE is just a convenience
wrapper over RAW IIRC", quoated from Peterz. So it could be pretty safe
to use the PERF_TYPE_RAW type only to program both gp and fixed
counters naturally in the reprogram_counter().
To make the gp and fixed counters more semantically symmetrical,
the selection of EVENTSEL_{USER, OS, INT} bits is temporarily translated
via fixed_ctr_ctrl before the pmc_reprogram_counter() call.
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 128 +++++++++++++----------------------
arch/x86/kvm/vmx/pmu_intel.c | 2 +-
2 files changed, 47 insertions(+), 83 deletions(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 5299488b002c..00e1660c10ca 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -215,85 +215,60 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
return allow_event;
}
-static void reprogram_gp_counter(struct kvm_pmc *pmc)
-{
- u64 config;
- u32 type = PERF_TYPE_RAW;
- u64 eventsel = pmc->eventsel;
-
- if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
- printk_once("kvm pmu: pin control bit is ignored\n");
-
- pmc_pause_counter(pmc);
-
- if (!(eventsel & ARCH_PERFMON_EVENTSEL_ENABLE) || !pmc_is_enabled(pmc))
- return;
-
- if (!check_pmu_event_filter(pmc))
- return;
-
- if (!(eventsel & (ARCH_PERFMON_EVENTSEL_EDGE |
- ARCH_PERFMON_EVENTSEL_INV |
- ARCH_PERFMON_EVENTSEL_CMASK |
- HSW_IN_TX |
- HSW_IN_TX_CHECKPOINTED))) {
- config = kvm_x86_ops.pmu_ops->pmc_perf_hw_id(pmc);
- if (config != PERF_COUNT_HW_MAX)
- type = PERF_TYPE_HARDWARE;
- }
-
- if (type == PERF_TYPE_RAW)
- config = eventsel & AMD64_RAW_EVENT_MASK;
-
- if (pmc->current_config == eventsel && pmc_resume_counter(pmc))
- return;
-
- pmc_release_perf_event(pmc);
-
- pmc->current_config = eventsel;
- pmc_reprogram_counter(pmc, type, config,
- !(eventsel & ARCH_PERFMON_EVENTSEL_USR),
- !(eventsel & ARCH_PERFMON_EVENTSEL_OS),
- eventsel & ARCH_PERFMON_EVENTSEL_INT,
- (eventsel & HSW_IN_TX),
- (eventsel & HSW_IN_TX_CHECKPOINTED));
-}
-
-static void reprogram_fixed_counter(struct kvm_pmc *pmc)
+static inline bool pmc_speculative_in_use(struct kvm_pmc *pmc)
{
struct kvm_pmu *pmu = pmc_to_pmu(pmc);
- int idx = pmc->idx - INTEL_PMC_IDX_FIXED;
- u8 ctrl = fixed_ctrl_field(pmu->fixed_ctr_ctrl, idx);
- unsigned en_field = ctrl & 0x3;
- bool pmi = ctrl & 0x8;
- pmc_pause_counter(pmc);
+ if (pmc_is_fixed(pmc))
+ return fixed_ctrl_field(pmu->fixed_ctr_ctrl,
+ pmc->idx - INTEL_PMC_IDX_FIXED) & 0x3;
- if (!en_field || !pmc_is_enabled(pmc))
- return;
-
- if (!check_pmu_event_filter(pmc))
- return;
-
- if (pmc->current_config == (u64)ctrl && pmc_resume_counter(pmc))
- return;
-
- pmc_release_perf_event(pmc);
-
- pmc->current_config = (u64)ctrl;
- pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
- kvm_x86_ops.pmu_ops->pmc_perf_hw_id(pmc),
- !(en_field & 0x2), /* exclude user */
- !(en_field & 0x1), /* exclude kernel */
- pmi, false, false);
+ return pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE;
}
void reprogram_counter(struct kvm_pmc *pmc)
{
- if (pmc_is_gp(pmc))
- reprogram_gp_counter(pmc);
- else
- reprogram_fixed_counter(pmc);
+ struct kvm_pmu *pmu = pmc_to_pmu(pmc);
+ u64 eventsel = pmc->eventsel;
+ u64 new_config = eventsel;
+ u8 fixed_ctr_ctrl;
+
+ pmc_pause_counter(pmc);
+
+ if (!pmc_speculative_in_use(pmc) || !pmc_is_enabled(pmc))
+ return;
+
+ if (!check_pmu_event_filter(pmc))
+ return;
+
+ if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
+ printk_once("kvm pmu: pin control bit is ignored\n");
+
+ if (pmc_is_fixed(pmc)) {
+ fixed_ctr_ctrl = fixed_ctrl_field(pmu->fixed_ctr_ctrl,
+ pmc->idx - INTEL_PMC_IDX_FIXED);
+ if (fixed_ctr_ctrl & 0x1)
+ eventsel |= ARCH_PERFMON_EVENTSEL_OS;
+ if (fixed_ctr_ctrl & 0x2)
+ eventsel |= ARCH_PERFMON_EVENTSEL_USR;
+ if (fixed_ctr_ctrl & 0x8)
+ eventsel |= ARCH_PERFMON_EVENTSEL_INT;
+ new_config = (u64)fixed_ctr_ctrl;
+ }
+
+ if (pmc->current_config == new_config && pmc_resume_counter(pmc))
+ return;
+
+ pmc_release_perf_event(pmc);
+
+ pmc->current_config = new_config;
+ pmc_reprogram_counter(pmc, PERF_TYPE_RAW,
+ (eventsel & AMD64_RAW_EVENT_MASK),
+ !(eventsel & ARCH_PERFMON_EVENTSEL_USR),
+ !(eventsel & ARCH_PERFMON_EVENTSEL_OS),
+ eventsel & ARCH_PERFMON_EVENTSEL_INT,
+ (eventsel & HSW_IN_TX),
+ (eventsel & HSW_IN_TX_CHECKPOINTED));
It seems that this extremely long argument list was motivated by the
differences between the two original call sites. Now that you have
mocked up a full eventsel (with USR, OS, INT, IN_TX, and IN_TXCP bits)
for the fixed counters, why not pass the entire eventsel as the third
I've thought about it.
I'm trying to pass-in generic bits (EVENT_MASK, USER, OS, INT) to
pmc_reprogram_counter() and let the latter handle the implementation details
of assembling the "struct perf_event_attr" to talk carefully with perf core.
I suppose the fixed counters doesn't support IN_TX* bits and I try to
clean those two away in another patch as you know.
In terms of code readability, the current one achieves a good balance.
argument and drop all of the rest? Then, pmc_reprogram_counter() can
extract/check the bits of interest.
}
EXPORT_SYMBOL_GPL(reprogram_counter);
@@ -451,17 +426,6 @@ void kvm_pmu_init(struct kvm_vcpu *vcpu)
kvm_pmu_refresh(vcpu);
}
-static inline bool pmc_speculative_in_use(struct kvm_pmc *pmc)
-{
- struct kvm_pmu *pmu = pmc_to_pmu(pmc);
-
- if (pmc_is_fixed(pmc))
- return fixed_ctrl_field(pmu->fixed_ctr_ctrl,
- pmc->idx - INTEL_PMC_IDX_FIXED) & 0x3;
-
- return pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE;
-}
-
/* Release perf_events for vPMCs that have been unused for a full time slice. */
void kvm_pmu_cleanup(struct kvm_vcpu *vcpu)
{
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 19b78a9d9d47..d823fbe4e155 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -492,7 +492,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
pmu->reserved_bits = 0xffffffff00200000ull;
entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
- if (!entry || !vcpu->kvm->arch.enable_pmu)
+ if (!entry || !vcpu->kvm->arch.enable_pmu || !boot_cpu_has(X86_FEATURE_ARCH_PERFMON))
This change seems unrelated.
The intention of using the PERF_TYPE_HARDWARE type is to emulate guest architecture
PMU on a host without architecture PMU (the oldest Pentium 4), for which the
guest vPMC
needs to be reprogrammed using the kernel generic perf_hw_id.
This is the most original story of PERF_TYPE_HARDWARE, thanks to history teacher
Paolo,
who also suggested this way to drop this kind of support.
return;
eax.full = entry->eax;
edx.full = entry->edx;
--
2.35.1
