diff options
Diffstat (limited to '0065-x86-vpmu-Fix-race-condition-in-vpmu_load.patch')
| -rw-r--r-- | 0065-x86-vpmu-Fix-race-condition-in-vpmu_load.patch | 97 |
1 files changed, 0 insertions, 97 deletions
diff --git a/0065-x86-vpmu-Fix-race-condition-in-vpmu_load.patch b/0065-x86-vpmu-Fix-race-condition-in-vpmu_load.patch deleted file mode 100644 index 84edf5d..0000000 --- a/0065-x86-vpmu-Fix-race-condition-in-vpmu_load.patch +++ /dev/null @@ -1,97 +0,0 @@ -From 9690bb261d5fa09cb281e1fa124d93db7b84fda5 Mon Sep 17 00:00:00 2001 -From: Tamas K Lengyel <tamas.lengyel@intel.com> -Date: Tue, 11 Oct 2022 15:17:42 +0200 -Subject: [PATCH 065/126] x86/vpmu: Fix race-condition in vpmu_load - -The vPMU code-bases attempts to perform an optimization on saving/reloading the -PMU context by keeping track of what vCPU ran on each pCPU. When a pCPU is -getting scheduled, checks if the previous vCPU isn't the current one. If so, -attempts a call to vpmu_save_force. Unfortunately if the previous vCPU is -already getting scheduled to run on another pCPU its state will be already -runnable, which results in an ASSERT failure. - -Fix this by always performing a pmu context save in vpmu_save when called from -vpmu_switch_from, and do a vpmu_load when called from vpmu_switch_to. - -While this presents a minimal overhead in case the same vCPU is getting -rescheduled on the same pCPU, the ASSERT failure is avoided and the code is a -lot easier to reason about. - -Signed-off-by: Tamas K Lengyel <tamas.lengyel@intel.com> -Acked-by: Jan Beulich <jbeulich@suse.com> -master commit: defa4e51d20a143bdd4395a075bf0933bb38a9a4 -master date: 2022-09-30 09:53:49 +0200 ---- - xen/arch/x86/cpu/vpmu.c | 42 ++++------------------------------------- - 1 file changed, 4 insertions(+), 38 deletions(-) - -diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c -index fb1b296a6cc1..800eff87dc03 100644 ---- a/xen/arch/x86/cpu/vpmu.c -+++ b/xen/arch/x86/cpu/vpmu.c -@@ -364,58 +364,24 @@ void vpmu_save(struct vcpu *v) - vpmu->last_pcpu = pcpu; - per_cpu(last_vcpu, pcpu) = v; - -+ vpmu_set(vpmu, VPMU_CONTEXT_SAVE); -+ - if ( vpmu->arch_vpmu_ops ) - if ( vpmu->arch_vpmu_ops->arch_vpmu_save(v, 0) ) - vpmu_reset(vpmu, VPMU_CONTEXT_LOADED); - -+ vpmu_reset(vpmu, VPMU_CONTEXT_SAVE); -+ - apic_write(APIC_LVTPC, PMU_APIC_VECTOR | APIC_LVT_MASKED); - } - - int vpmu_load(struct vcpu *v, bool_t from_guest) - { - struct vpmu_struct *vpmu = vcpu_vpmu(v); -- int pcpu = smp_processor_id(); -- struct vcpu *prev = NULL; - - if ( !vpmu_is_set(vpmu, VPMU_CONTEXT_ALLOCATED) ) - return 0; - -- /* First time this VCPU is running here */ -- if ( vpmu->last_pcpu != pcpu ) -- { -- /* -- * Get the context from last pcpu that we ran on. Note that if another -- * VCPU is running there it must have saved this VPCU's context before -- * startig to run (see below). -- * There should be no race since remote pcpu will disable interrupts -- * before saving the context. -- */ -- if ( vpmu_is_set(vpmu, VPMU_CONTEXT_LOADED) ) -- { -- on_selected_cpus(cpumask_of(vpmu->last_pcpu), -- vpmu_save_force, (void *)v, 1); -- vpmu_reset(vpmu, VPMU_CONTEXT_LOADED); -- } -- } -- -- /* Prevent forced context save from remote CPU */ -- local_irq_disable(); -- -- prev = per_cpu(last_vcpu, pcpu); -- -- if ( prev != v && prev ) -- { -- vpmu = vcpu_vpmu(prev); -- -- /* Someone ran here before us */ -- vpmu_save_force(prev); -- vpmu_reset(vpmu, VPMU_CONTEXT_LOADED); -- -- vpmu = vcpu_vpmu(v); -- } -- -- local_irq_enable(); -- - /* Only when PMU is counting, we load PMU context immediately. */ - if ( !vpmu_is_set(vpmu, VPMU_RUNNING) || - (!has_vlapic(vpmu_vcpu(vpmu)->domain) && --- -2.37.4 - |