diff options
-rw-r--r-- | Documentation/virt/kvm/vcpu-requests.rst | 10 | ||||
-rw-r--r-- | arch/s390/kvm/kvm-s390.c | 2 | ||||
-rw-r--r-- | include/linux/kvm_host.h | 38 | ||||
-rw-r--r-- | virt/kvm/kvm_main.c | 3 | ||||
-rw-r--r-- | virt/kvm/pfncache.c | 18 |
5 files changed, 55 insertions, 16 deletions
diff --git a/Documentation/virt/kvm/vcpu-requests.rst b/Documentation/virt/kvm/vcpu-requests.rst index b61d48aec36c..db43ee571f5a 100644 --- a/Documentation/virt/kvm/vcpu-requests.rst +++ b/Documentation/virt/kvm/vcpu-requests.rst @@ -135,6 +135,16 @@ KVM_REQ_UNHALT such as a pending signal, which does not indicate the VCPU's halt emulation should stop, and therefore does not make the request. +KVM_REQ_OUTSIDE_GUEST_MODE + + This "request" ensures the target vCPU has exited guest mode prior to the + sender of the request continuing on. No action needs be taken by the target, + and so no request is actually logged for the target. This request is similar + to a "kick", but unlike a kick it guarantees the vCPU has actually exited + guest mode. A kick only guarantees the vCPU will exit at some point in the + future, e.g. a previous kick may have started the process, but there's no + guarantee the to-be-kicked vCPU has fully exited guest mode. + KVM_REQUEST_MASK ---------------- diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index ca96f84db2cc..91c0cefc94aa 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3463,7 +3463,7 @@ void exit_sie(struct kvm_vcpu *vcpu) /* Kick a guest cpu out of SIE to process a request synchronously */ void kvm_s390_sync_request(int req, struct kvm_vcpu *vcpu) { - kvm_make_request(req, vcpu); + __kvm_make_request(req, vcpu); kvm_s390_vcpu_request(vcpu); } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9536ffa0473b..678fd7914521 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -148,6 +148,7 @@ 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) +#define KVM_REQUEST_NO_ACTION BIT(10) /* * Architecture-independent vcpu->requests bit members * Bits 4-7 are reserved for more arch-independent bits. @@ -156,9 +157,18 @@ static inline bool is_error_page(struct page *page) #define KVM_REQ_VM_DEAD (1 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQ_UNBLOCK 2 #define KVM_REQ_UNHALT 3 -#define KVM_REQ_GPC_INVALIDATE (5 | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) #define KVM_REQUEST_ARCH_BASE 8 +/* + * KVM_REQ_OUTSIDE_GUEST_MODE exists is purely as way to force the vCPU to + * OUTSIDE_GUEST_MODE. KVM_REQ_OUTSIDE_GUEST_MODE differs from a vCPU "kick" + * in that it ensures the vCPU has reached OUTSIDE_GUEST_MODE before continuing + * on. A kick only guarantees that the vCPU is on its way out, e.g. a previous + * kick may have set vcpu->mode to EXITING_GUEST_MODE, and so there's no + * guarantee the vCPU received an IPI and has actually exited guest mode. + */ +#define KVM_REQ_OUTSIDE_GUEST_MODE (KVM_REQUEST_NO_ACTION | KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) + #define KVM_ARCH_REQ_FLAGS(nr, flags) ({ \ BUILD_BUG_ON((unsigned)(nr) >= (sizeof_field(struct kvm_vcpu, requests) * 8) - KVM_REQUEST_ARCH_BASE); \ (unsigned)(((nr) + KVM_REQUEST_ARCH_BASE) | (flags)); \ @@ -1222,7 +1232,9 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn); * @vcpu: vCPU to be used for marking pages dirty and to be woken on * invalidation. * @guest_uses_pa: indicates that the resulting host physical PFN is used while - * @vcpu is IN_GUEST_MODE so invalidations should wake it. + * @vcpu is IN_GUEST_MODE; invalidations of the cache from MMU + * notifiers (but not for KVM memslot changes!) will also force + * @vcpu to exit the guest to refresh the cache. * @kernel_map: requests a kernel virtual mapping (kmap / memremap). * @gpa: guest physical address to map. * @len: sanity check; the range being access must fit a single page. @@ -1233,10 +1245,9 @@ void kvm_vcpu_mark_page_dirty(struct kvm_vcpu *vcpu, gfn_t gfn); * -EFAULT for an untranslatable guest physical address. * * This primes a gfn_to_pfn_cache and links it into the @kvm's list for - * invalidations to be processed. Invalidation callbacks to @vcpu using - * %KVM_REQ_GPC_INVALIDATE will occur only for MMU notifiers, not for KVM - * memslot changes. Callers are required to use kvm_gfn_to_pfn_cache_check() - * to ensure that the cache is valid before accessing the target page. + * invalidations to be processed. Callers are required to use + * kvm_gfn_to_pfn_cache_check() to ensure that the cache is valid before + * accessing the target page. */ int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, struct kvm_vcpu *vcpu, bool guest_uses_pa, @@ -1984,7 +1995,7 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) void kvm_arch_irq_routing_update(struct kvm *kvm); -static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) +static inline void __kvm_make_request(int req, struct kvm_vcpu *vcpu) { /* * Ensure the rest of the request is published to kvm_check_request's @@ -1994,6 +2005,19 @@ static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) set_bit(req & KVM_REQUEST_MASK, (void *)&vcpu->requests); } +static __always_inline void kvm_make_request(int req, struct kvm_vcpu *vcpu) +{ + /* + * Request that don't require vCPU action should never be logged in + * vcpu->requests. The vCPU won't clear the request, so it will stay + * logged indefinitely and prevent the vCPU from entering the guest. + */ + BUILD_BUG_ON(!__builtin_constant_p(req) || + (req & KVM_REQUEST_NO_ACTION)); + + __kvm_make_request(req, vcpu); +} + static inline bool kvm_request_pending(struct kvm_vcpu *vcpu) { return READ_ONCE(vcpu->requests); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 11267d5e4c52..70e05af5ebea 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -253,7 +253,8 @@ static void kvm_make_vcpu_request(struct kvm_vcpu *vcpu, unsigned int req, { int cpu; - kvm_make_request(req, vcpu); + if (likely(!(req & KVM_REQUEST_NO_ACTION))) + __kvm_make_request(req, vcpu); if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu)) return; diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index 1621f8efd961..81b2758d0ded 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -27,7 +27,7 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, { DECLARE_BITMAP(vcpu_bitmap, KVM_MAX_VCPUS); struct gfn_to_pfn_cache *gpc; - bool wake_vcpus = false; + bool evict_vcpus = false; spin_lock(&kvm->gpc_lock); list_for_each_entry(gpc, &kvm->gpc_list, list) { @@ -40,11 +40,11 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, /* * If a guest vCPU could be using the physical address, - * it needs to be woken. + * it needs to be forced out of guest mode. */ if (gpc->guest_uses_pa) { - if (!wake_vcpus) { - wake_vcpus = true; + if (!evict_vcpus) { + evict_vcpus = true; bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS); } __set_bit(gpc->vcpu->vcpu_idx, vcpu_bitmap); @@ -67,14 +67,18 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start, } spin_unlock(&kvm->gpc_lock); - if (wake_vcpus) { - unsigned int req = KVM_REQ_GPC_INVALIDATE; + if (evict_vcpus) { + /* + * KVM needs to ensure the vCPU is fully out of guest context + * before allowing the invalidation to continue. + */ + unsigned int req = KVM_REQ_OUTSIDE_GUEST_MODE; bool called; /* * If the OOM reaper is active, then all vCPUs should have * been stopped already, so perform the request without - * KVM_REQUEST_WAIT and be sad if any needed to be woken. + * KVM_REQUEST_WAIT and be sad if any needed to be IPI'd. */ if (!may_block) req &= ~KVM_REQUEST_WAIT; |