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authorLike Xu <likexu@tencent.com>2022-09-23 00:13:55 +0000
committerPaolo Bonzini <pbonzini@redhat.com>2022-11-09 12:31:36 -0500
commitde0f619564f4713bd548b82d535a954ffa1ee7d8 (patch)
tree0e583bf78ddea68200b42020680ee80de52d2e55 /arch/x86/kvm/pmu.c
parent68fb4757e8678894530ee0b15c29a3567207b970 (diff)
KVM: x86/pmu: Defer counter emulated overflow via pmc->prev_counter
Defer reprogramming counters and handling overflow via KVM_REQ_PMU when incrementing counters. KVM skips emulated WRMSR in the VM-Exit fastpath, the fastpath runs with IRQs disabled, skipping instructions can increment and reprogram counters, reprogramming counters can sleep, and sleeping is disallowed while IRQs are disabled. [*] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 [*] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2981888, name: CPU 15/KVM [*] preempt_count: 1, expected: 0 [*] RCU nest depth: 0, expected: 0 [*] INFO: lockdep is turned off. [*] irq event stamp: 0 [*] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [*] hardirqs last disabled at (0): [<ffffffff8121222a>] copy_process+0x146a/0x62d0 [*] softirqs last enabled at (0): [<ffffffff81212269>] copy_process+0x14a9/0x62d0 [*] softirqs last disabled at (0): [<0000000000000000>] 0x0 [*] Preemption disabled at: [*] [<ffffffffc2063fc1>] vcpu_enter_guest+0x1001/0x3dc0 [kvm] [*] CPU: 17 PID: 2981888 Comm: CPU 15/KVM Kdump: 5.19.0-rc1-g239111db364c-dirty #2 [*] Call Trace: [*] <TASK> [*] dump_stack_lvl+0x6c/0x9b [*] __might_resched.cold+0x22e/0x297 [*] __mutex_lock+0xc0/0x23b0 [*] perf_event_ctx_lock_nested+0x18f/0x340 [*] perf_event_pause+0x1a/0x110 [*] reprogram_counter+0x2af/0x1490 [kvm] [*] kvm_pmu_trigger_event+0x429/0x950 [kvm] [*] kvm_skip_emulated_instruction+0x48/0x90 [kvm] [*] handle_fastpath_set_msr_irqoff+0x349/0x3b0 [kvm] [*] vmx_vcpu_run+0x268e/0x3b80 [kvm_intel] [*] vcpu_enter_guest+0x1d22/0x3dc0 [kvm] Add a field to kvm_pmc to track the previous counter value in order to defer overflow detection to kvm_pmu_handle_event() (the counter must be paused before handling overflow, and that may increment the counter). Opportunistically shrink sizeof(struct kvm_pmc) a bit. Suggested-by: Wanpeng Li <wanpengli@tencent.com> Fixes: 9cd803d496e7 ("KVM: x86: Update vPMCs when retiring instructions") Signed-off-by: Like Xu <likexu@tencent.com> Link: https://lore.kernel.org/r/20220831085328.45489-6-likexu@tencent.com [sean: avoid re-triggering KVM_REQ_PMU on overflow, tweak changelog] Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220923001355.3741194-5-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/pmu.c')
-rw-r--r--arch/x86/kvm/pmu.c32
1 files changed, 16 insertions, 16 deletions
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 3054b35b4143..684393c22105 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -101,14 +101,6 @@ static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi)
struct kvm_pmu *pmu = pmc_to_pmu(pmc);
bool skip_pmi = false;
- /*
- * Ignore overflow events for counters that are scheduled to be
- * reprogrammed, e.g. if a PMI for the previous event races with KVM's
- * handling of a related guest WRMSR.
- */
- if (test_and_set_bit(pmc->idx, pmu->reprogram_pmi))
- return;
-
if (pmc->perf_event && pmc->perf_event->attr.precise_ip) {
if (!in_pmi) {
/*
@@ -126,7 +118,6 @@ static inline void __kvm_perf_overflow(struct kvm_pmc *pmc, bool in_pmi)
} else {
__set_bit(pmc->idx, (unsigned long *)&pmu->global_status);
}
- kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
if (!pmc->intr || skip_pmi)
return;
@@ -151,7 +142,17 @@ static void kvm_perf_overflow(struct perf_event *perf_event,
{
struct kvm_pmc *pmc = perf_event->overflow_handler_context;
+ /*
+ * Ignore overflow events for counters that are scheduled to be
+ * reprogrammed, e.g. if a PMI for the previous event races with KVM's
+ * handling of a related guest WRMSR.
+ */
+ if (test_and_set_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi))
+ return;
+
__kvm_perf_overflow(pmc, true);
+
+ kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
}
static int pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, u64 config,
@@ -311,6 +312,9 @@ static void reprogram_counter(struct kvm_pmc *pmc)
if (!check_pmu_event_filter(pmc))
goto reprogram_complete;
+ if (pmc->counter < pmc->prev_counter)
+ __kvm_perf_overflow(pmc, false);
+
if (eventsel & ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
printk_once("kvm pmu: pin control bit is ignored\n");
@@ -348,6 +352,7 @@ static void reprogram_counter(struct kvm_pmc *pmc)
reprogram_complete:
clear_bit(pmc->idx, (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);
+ pmc->prev_counter = 0;
}
void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
@@ -536,14 +541,9 @@ void kvm_pmu_destroy(struct kvm_vcpu *vcpu)
static void kvm_pmu_incr_counter(struct kvm_pmc *pmc)
{
- u64 prev_count;
-
- prev_count = pmc->counter;
+ pmc->prev_counter = pmc->counter;
pmc->counter = (pmc->counter + 1) & pmc_bitmask(pmc);
-
- reprogram_counter(pmc);
- if (pmc->counter < prev_count)
- __kvm_perf_overflow(pmc, false);
+ kvm_pmu_request_counter_reprogam(pmc);
}
static inline bool eventsel_match_perf_hw_id(struct kvm_pmc *pmc,