From 17e433b54393a6269acbcb792da97791fe1592d8 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 5 Aug 2019 10:03:19 +0800 Subject: KVM: Fix leak vCPU's VMCS value into other pCPU MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit After commit d73eb57b80b (KVM: Boost vCPUs that are delivering interrupts), a five years old bug is exposed. Running ebizzy benchmark in three 80 vCPUs VMs on one 80 pCPUs Skylake server, a lot of rcu_sched stall warning splatting in the VMs after stress testing: INFO: rcu_sched detected stalls on CPUs/tasks: { 4 41 57 62 77} (detected by 15, t=60004 jiffies, g=899, c=898, q=15073) Call Trace: flush_tlb_mm_range+0x68/0x140 tlb_flush_mmu.part.75+0x37/0xe0 tlb_finish_mmu+0x55/0x60 zap_page_range+0x142/0x190 SyS_madvise+0x3cd/0x9c0 system_call_fastpath+0x1c/0x21 swait_active() sustains to be true before finish_swait() is called in kvm_vcpu_block(), voluntarily preempted vCPUs are taken into account by kvm_vcpu_on_spin() loop greatly increases the probability condition kvm_arch_vcpu_runnable(vcpu) is checked and can be true, when APICv is enabled the yield-candidate vCPU's VMCS RVI field leaks(by vmx_sync_pir_to_irr()) into spinning-on-a-taken-lock vCPU's current VMCS. This patch fixes it by checking conservatively a subset of events. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Christian Borntraeger Cc: Marc Zyngier Cc: stable@vger.kernel.org Fixes: 98f4a1467 (KVM: add kvm_arch_vcpu_runnable() test to kvm_vcpu_on_spin() loop) Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 5c5b5867024c..9e4c2bb90297 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -872,6 +872,7 @@ int kvm_arch_check_processor_compat(void); int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu); bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu); int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu); +bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu); #ifndef __KVM_HAVE_ARCH_VM_ALLOC /* -- cgit v1.2.3 From 741cbbae0768b828be2d48331eb371a4f08bbea8 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Sat, 3 Aug 2019 08:14:25 +0200 Subject: KVM: remove kvm_arch_has_vcpu_debugfs() There is no need for this function as all arches have to implement kvm_arch_create_vcpu_debugfs() no matter what. A #define symbol let us actually simplify the code. Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9e4c2bb90297..8d34db3c8bc6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -861,8 +861,9 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu); -bool kvm_arch_has_vcpu_debugfs(void); +#ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu); +#endif int kvm_arch_hardware_enable(void); void kvm_arch_hardware_disable(void); -- cgit v1.2.3 From 3e7093d045196b1016517631645e874fe903db7e Mon Sep 17 00:00:00 2001 From: Greg KH Date: Wed, 31 Jul 2019 20:56:20 +0200 Subject: KVM: no need to check return value of debugfs_create functions MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this. Also, when doing this, change kvm_arch_create_vcpu_debugfs() to return void instead of an integer, as we should not care at all about if this function actually does anything or not. Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Cc: Signed-off-by: Greg Kroah-Hartman Signed-off-by: Paolo Bonzini --- include/linux/kvm_host.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 8d34db3c8bc6..fcb46b3374c6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -862,7 +862,7 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu); #ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS -int kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu); +void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu); #endif int kvm_arch_hardware_enable(void); -- cgit v1.2.3