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KVM/arm fixes for 5.4, take #2 

Special PMU edition:
 
 - Fix cycle counter truncation
 - Fix cycle counter overflow limit on pure 64bit system
 - Allow chained events to be actually functional
 - Correct sample period after overflow
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Merge tag 'kvmarm-fixes-5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm fixes for 5.4, take #2

Special PMU edition:

- Fix cycle counter truncation
- Fix cycle counter overflow limit on pure 64bit system
- Allow chained events to be actually functional
- Correct sample period after overflow
This commit is contained in:
Paolo Bonzini 2019-10-22 13:31:29 +02:00
parent 49dedf0dd0 8c3252c065
commit 9800c24e2f
2 changed files with 39 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/kvm/sys_regs.c
View File

@ -632,6 +632,8 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
*/
val = ((pmcr & ~ARMV8_PMU_PMCR_MASK)
| (ARMV8_PMU_PMCR_MASK & 0xdecafbad)) & (~ARMV8_PMU_PMCR_E);
if (!system_supports_32bit_el0())
val |= ARMV8_PMU_PMCR_LC;
__vcpu_sys_reg(vcpu, r->reg) = val;
}
@ -682,6 +684,8 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
val = __vcpu_sys_reg(vcpu, PMCR_EL0);
val &= ~ARMV8_PMU_PMCR_MASK;
val |= p->regval & ARMV8_PMU_PMCR_MASK;
if (!system_supports_32bit_el0())
val |= ARMV8_PMU_PMCR_LC;
__vcpu_sys_reg(vcpu, PMCR_EL0) = val;
kvm_pmu_handle_pmcr(vcpu, val);
kvm_vcpu_pmu_restore_guest(vcpu);

48
virt/kvm/arm/pmu.c
View File

@ -8,6 +8,7 @@
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
#include <linux/perf/arm_pmu.h>
#include <linux/uaccess.h>
#include <asm/kvm_emulate.h>
#include <kvm/arm_pmu.h>
@ -146,8 +147,7 @@ u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx)
if (kvm_pmu_pmc_is_chained(pmc) &&
kvm_pmu_idx_is_high_counter(select_idx))
counter = upper_32_bits(counter);
else if (!kvm_pmu_idx_is_64bit(vcpu, select_idx))
else if (select_idx != ARMV8_PMU_CYCLE_IDX)
counter = lower_32_bits(counter);
return counter;
@ -193,7 +193,7 @@ static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc)
*/
static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
{
u64 counter, reg;
u64 counter, reg, val;
pmc = kvm_pmu_get_canonical_pmc(pmc);
if (!pmc->perf_event)
@ -201,16 +201,19 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
counter = kvm_pmu_get_pair_counter_value(vcpu, pmc);
if (kvm_pmu_pmc_is_chained(pmc)) {
reg = PMEVCNTR0_EL0 + pmc->idx;
__vcpu_sys_reg(vcpu, reg) = lower_32_bits(counter);
__vcpu_sys_reg(vcpu, reg + 1) = upper_32_bits(counter);
if (pmc->idx == ARMV8_PMU_CYCLE_IDX) {
reg = PMCCNTR_EL0;
val = counter;
} else {
reg = (pmc->idx == ARMV8_PMU_CYCLE_IDX)
? PMCCNTR_EL0 : PMEVCNTR0_EL0 + pmc->idx;
__vcpu_sys_reg(vcpu, reg) = lower_32_bits(counter);
reg = PMEVCNTR0_EL0 + pmc->idx;
val = lower_32_bits(counter);
}
__vcpu_sys_reg(vcpu, reg) = val;
if (kvm_pmu_pmc_is_chained(pmc))
__vcpu_sys_reg(vcpu, reg + 1) = upper_32_bits(counter);
kvm_pmu_release_perf_event(pmc);
}
@ -440,8 +443,25 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
struct pt_regs *regs)
{
struct kvm_pmc *pmc = perf_event->overflow_handler_context;
struct arm_pmu *cpu_pmu = to_arm_pmu(perf_event->pmu);
struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
int idx = pmc->idx;
u64 period;
cpu_pmu->pmu.stop(perf_event, PERF_EF_UPDATE);
/*
* Reset the sample period to the architectural limit,
* i.e. the point where the counter overflows.
*/
period = -(local64_read(&perf_event->count));
if (!kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
period &= GENMASK(31, 0);
local64_set(&perf_event->hw.period_left, 0);
perf_event->attr.sample_period = period;
perf_event->hw.sample_period = period;
__vcpu_sys_reg(vcpu, PMOVSSET_EL0) |= BIT(idx);
@ -449,6 +469,8 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
kvm_vcpu_kick(vcpu);
}
cpu_pmu->pmu.start(perf_event, PERF_EF_RELOAD);
}
/**
@ -567,12 +589,12 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
* high counter.
*/
attr.sample_period = (-counter) & GENMASK(63, 0);
if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
event = perf_event_create_kernel_counter(&attr, -1, current,
kvm_pmu_perf_overflow,
pmc + 1);
if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
} else {
/* The initial sample period (overflow count) of an event. */
if (kvm_pmu_idx_is_64bit(vcpu, pmc->idx))