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-rw-r--r--Documentation/virt/kvm/vcpu-requests.rst10
-rw-r--r--arch/s390/kvm/kvm-s390.c2
-rw-r--r--include/linux/kvm_host.h38
-rw-r--r--virt/kvm/kvm_main.c3
-rw-r--r--virt/kvm/pfncache.c18
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;
generated by cgit v1.2.3-70-g09d2 (git 2.47.1) at 2024-12-27 11:56:12 +0000