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. A question is whether this propertly isn't better expressed as a function of the caller. Signed-off-by: Radim Krčmář <[email protected]> --- v2: replaces [v1 1/6] Ugh, KVM_ARCH_REQ_WAIT_NO_WAKEUP looks a weird ... --- 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 | 8 ++++++-- virt/kvm/kvm_main.c | 16 +++++++++++++--- 5 files changed, 24 insertions(+), 10 deletions(-) diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 1d48a4b65b86..2190a7ddd515 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 KVM_ARCH_REQ_NO_WAKEUP(0) +#define KVM_REQ_VCPU_EXIT KVM_ARCH_REQ_WAIT_NO_WAKEUP(0) 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 d3370b79660e..98f3d01ae91b 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 KVM_ARCH_REQ_NO_WAKEUP(0) +#define KVM_REQ_VCPU_EXIT KVM_ARCH_REQ_WAIT_NO_WAKEUP(0) 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 15eb7d3837e3..77083d7e9540 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 KVM_ARCH_REQ(11) #define KVM_REQ_SMI KVM_ARCH_REQ(12) #define KVM_REQ_MASTERCLOCK_UPDATE KVM_ARCH_REQ(13) -#define KVM_REQ_MCLOCK_INPROGRESS KVM_ARCH_REQ_NO_WAKEUP(14) -#define KVM_REQ_SCAN_IOAPIC KVM_ARCH_REQ_NO_WAKEUP(15) +#define KVM_REQ_MCLOCK_INPROGRESS KVM_ARCH_REQ_WAIT_NO_WAKEUP(14) +#define KVM_REQ_SCAN_IOAPIC KVM_ARCH_REQ_WAIT_NO_WAKEUP(15) #define KVM_REQ_GLOBAL_CLOCK_UPDATE KVM_ARCH_REQ(16) -#define KVM_REQ_APIC_PAGE_RELOAD KVM_ARCH_REQ_NO_WAKEUP(17) +#define KVM_REQ_APIC_PAGE_RELOAD KVM_ARCH_REQ_WAIT_NO_WAKEUP(17) #define KVM_REQ_HV_CRASH KVM_ARCH_REQ(18) #define KVM_REQ_IOAPIC_EOI_EXIT KVM_ARCH_REQ(19) #define KVM_REQ_HV_RESET KVM_ARCH_REQ(20) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 38cfe372918c..a668f33b20dc 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -117,12 +117,13 @@ 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_TLB_FLUSH (0 | KVM_REQUEST_NO_WAKEUP | KVM_REQUEST_WAIT) +#define KVM_REQ_MMU_RELOAD (1 | KVM_REQUEST_NO_WAKEUP | KVM_REQUEST_WAIT) #define KVM_REQ_PENDING_TIMER 2 #define KVM_REQ_UNHALT 3 #define KVM_REQUEST_ARCH_BASE 8 @@ -133,6 +134,9 @@ static inline bool is_error_page(struct page *page) }) #define KVM_ARCH_REQ(nr) KVM_ARCH_REQ_FLAGS(nr, 0) #define KVM_ARCH_REQ_NO_WAKEUP(nr) KVM_ARCH_REQ_FLAGS(nr, KVM_REQUEST_NO_WAKEUP) +#define KVM_ARCH_REQ_WAIT(nr) KVM_ARCH_REQ_FLAGS(nr, KVM_REQUEST_NO_WAKEUP) +#define KVM_ARCH_REQ_WAIT_NO_WAKEUP(nr) \ + KVM_ARCH_REQ_FLAGS(nr, KVM_REQUEST_NO_WAKEUP | KVM_REQUEST_WAIT) #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 632f7b3e198c..dbf0410cd8b2 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -165,6 +165,15 @@ void vcpu_put(struct kvm_vcpu *vcpu) } EXPORT_SYMBOL_GPL(vcpu_put); +/* TODO: merge with kvm_arch_vcpu_should_kick */ +static bool kvm_should_kick_request(struct kvm_vcpu *vcpu, unsigned req) +{ + int mode = kvm_vcpu_exiting_guest_mode(vcpu); + + return req & KVM_REQUEST_WAIT ? + mode != OUTSIDE_GUEST_MODE : mode == IN_GUEST_MODE; +} + static void ack_flush(void *_completed) { } @@ -174,6 +183,7 @@ 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 +197,13 @@ 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_should_kick_request(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(); -- 2.12.2
