From 7a97cec26b94c909f4cbad2dc3186af3e457a522 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 27 Apr 2017 14:33:43 +0200 Subject: [PATCH] KVM: mark requests that need synchronization MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit kvm_make_all_requests() provides a synchronization that waits until all kicked VCPUs have acknowledged the kick. This is important for KVM_REQ_MMU_RELOAD as it prevents freeing while lockless paging is underway. This patch adds the synchronization property into all requests that are currently being used with kvm_make_all_requests() in order to preserve the current behavior and only introduce a new framework. Removing it from requests where it is not necessary is left for future patches. Signed-off-by: Radim Krčmář Signed-off-by: Paolo Bonzini --- arch/arm/include/asm/kvm_host.h | 2 +- arch/arm64/include/asm/kvm_host.h | 2 +- arch/x86/include/asm/kvm_host.h | 6 +++--- include/linux/kvm_host.h | 9 +++++---- virt/kvm/kvm_main.c | 25 ++++++++++++++++++++++--- 5 files changed, 32 insertions(+), 12 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 49358f2..3cd04d1 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -44,7 +44,7 @@ #define KVM_MAX_VCPUS VGIC_V2_MAX_CPUS #endif -#define KVM_REQ_VCPU_EXIT (8 | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_VCPU_EXIT (8 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode); int __attribute_const__ kvm_target_cpu(void); diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 1c9458a..d239ae1 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -41,7 +41,7 @@ #define KVM_VCPU_MAX_FEATURES 4 -#define KVM_REQ_VCPU_EXIT (8 | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_VCPU_EXIT (8 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) int __attribute_const__ kvm_target_cpu(void); int kvm_reset_vcpu(struct kvm_vcpu *vcpu); diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 1921982..84c8489 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -61,10 +61,10 @@ #define KVM_REQ_PMI 19 #define KVM_REQ_SMI 20 #define KVM_REQ_MASTERCLOCK_UPDATE 21 -#define KVM_REQ_MCLOCK_INPROGRESS (22 | KVM_REQUEST_NO_WAKEUP) -#define KVM_REQ_SCAN_IOAPIC (23 | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_MCLOCK_INPROGRESS (22 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_SCAN_IOAPIC (23 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_GLOBAL_CLOCK_UPDATE 24 -#define KVM_REQ_APIC_PAGE_RELOAD (25 | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_APIC_PAGE_RELOAD (25 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_HV_CRASH 26 #define KVM_REQ_IOAPIC_EOI_EXIT 27 #define KVM_REQ_HV_RESET 28 diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index f4a2c00..a5bfffa8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -117,14 +117,15 @@ static inline bool is_error_page(struct page *page) #define KVM_REQUEST_MASK GENMASK(7,0) #define KVM_REQUEST_NO_WAKEUP BIT(8) +#define KVM_REQUEST_WAIT BIT(9) /* * Architecture-independent vcpu->requests bit members * Bits 4-7 are reserved for more arch-independent bits. */ -#define KVM_REQ_TLB_FLUSH (0 | KVM_REQUEST_NO_WAKEUP) -#define KVM_REQ_MMU_RELOAD (1 | KVM_REQUEST_NO_WAKEUP) -#define KVM_REQ_PENDING_TIMER 2 -#define KVM_REQ_UNHALT 3 +#define KVM_REQ_TLB_FLUSH (0 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_MMU_RELOAD (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) +#define KVM_REQ_PENDING_TIMER 2 +#define KVM_REQ_UNHALT 3 #define KVM_USERSPACE_IRQ_SOURCE_ID 0 #define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1 diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 632f7b3..035bc51 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -165,6 +165,24 @@ void vcpu_put(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(vcpu_put); +/* TODO: merge with kvm_arch_vcpu_should_kick */ +static bool kvm_request_needs_ipi(struct kvm_vcpu *vcpu, unsigned req) +{ + int mode = kvm_vcpu_exiting_guest_mode(vcpu); + + /* + * We need to wait for the VCPU to reenable interrupts and get out of + * READING_SHADOW_PAGE_TABLES mode. + */ + if (req & KVM_REQUEST_WAIT) + return mode != OUTSIDE_GUEST_MODE; + + /* + * Need to kick a running VCPU, but otherwise there is nothing to do. + */ + return mode == IN_GUEST_MODE; +} + static void ack_flush(void *_completed) { } @@ -174,6 +192,7 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) int i, cpu, me; cpumask_var_t cpus; bool called = true; + bool wait = req & KVM_REQUEST_WAIT; struct kvm_vcpu *vcpu; zalloc_cpumask_var(&cpus, GFP_ATOMIC); @@ -187,13 +206,13 @@ bool kvm_make_all_cpus_request(struct kvm *kvm, unsigned int req) continue; if (cpus != NULL && cpu != -1 && cpu != me && - kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE) + kvm_request_needs_ipi(vcpu, req)) cpumask_set_cpu(cpu, cpus); } if (unlikely(cpus == NULL)) - smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1); + smp_call_function_many(cpu_online_mask, ack_flush, NULL, wait); else if (!cpumask_empty(cpus)) - smp_call_function_many(cpus, ack_flush, NULL, 1); + smp_call_function_many(cpus, ack_flush, NULL, wait); else called = false; put_cpu(); -- 2.7.4