KVM: Use gfn_to_pfn_cache's immutable "kvm" in kvm_gpc_check()

Make kvm_gpc_check() use kvm instance cached in gfn_to_pfn_cache.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

arch/x86/kvm/x86.c

@@ -3035,7 +3035,7 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
 	unsigned long flags;
 
 	read_lock_irqsave(&gpc->lock, flags);
-	while (!kvm_gpc_check(v->kvm, gpc, gpc->gpa,
+	while (!kvm_gpc_check(gpc, gpc->gpa,
 			      offset + sizeof(*guest_hv_clock))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 

arch/x86/kvm/xen.c

@@ -272,7 +272,7 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
 	 * gfn_to_pfn caches that cover the region.
 	 */
 	read_lock_irqsave(&gpc1->lock, flags);
-	while (!kvm_gpc_check(v->kvm, gpc1, gpc1->gpa, user_len1)) {
+	while (!kvm_gpc_check(gpc1, gpc1->gpa, user_len1)) {
 		read_unlock_irqrestore(&gpc1->lock, flags);
 
 		/* When invoked from kvm_sched_out() we cannot sleep */
@@ -308,7 +308,7 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
 		 */
 		read_lock(&gpc2->lock);
 
-		if (!kvm_gpc_check(v->kvm, gpc2, gpc2->gpa, user_len2)) {
+		if (!kvm_gpc_check(gpc2, gpc2->gpa, user_len2)) {
 			read_unlock(&gpc2->lock);
 			read_unlock_irqrestore(&gpc1->lock, flags);
 
@@ -488,8 +488,7 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
 	 * little more honest about it.
 	 */
 	read_lock_irqsave(&gpc->lock, flags);
-	while (!kvm_gpc_check(v->kvm, gpc, gpc->gpa,
-			      sizeof(struct vcpu_info))) {
+	while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 
 		if (kvm_gpc_refresh(v->kvm, gpc, gpc->gpa,
@@ -553,8 +552,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
 		     sizeof_field(struct compat_vcpu_info, evtchn_upcall_pending));
 
 	read_lock_irqsave(&gpc->lock, flags);
-	while (!kvm_gpc_check(v->kvm, gpc, gpc->gpa,
-			      sizeof(struct vcpu_info))) {
+	while (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 
 		/*
@@ -1158,7 +1156,7 @@ static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports,
 
 	read_lock_irqsave(&gpc->lock, flags);
 	idx = srcu_read_lock(&kvm->srcu);
-	if (!kvm_gpc_check(kvm, gpc, gpc->gpa, PAGE_SIZE))
+	if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE))
 		goto out_rcu;
 
 	ret = false;
@@ -1580,7 +1578,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
 	idx = srcu_read_lock(&kvm->srcu);
 
 	read_lock_irqsave(&gpc->lock, flags);
-	if (!kvm_gpc_check(kvm, gpc, gpc->gpa, PAGE_SIZE))
+	if (!kvm_gpc_check(gpc, gpc->gpa, PAGE_SIZE))
 		goto out_rcu;
 
 	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
@@ -1614,7 +1612,7 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, struct kvm *kvm)
 		gpc = &vcpu->arch.xen.vcpu_info_cache;
 
 		read_lock_irqsave(&gpc->lock, flags);
-		if (!kvm_gpc_check(kvm, gpc, gpc->gpa, sizeof(struct vcpu_info))) {
+		if (!kvm_gpc_check(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
 			/*
 			 * Could not access the vcpu_info. Set the bit in-kernel
 			 * and prod the vCPU to deliver it for itself.

include/linux/kvm_host.h

@@ -1298,7 +1298,6 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
 /**
  * kvm_gpc_check - check validity of a gfn_to_pfn_cache.
  *
- * @kvm:	   pointer to kvm instance.
  * @gpc:	   struct gfn_to_pfn_cache object.
  * @gpa:	   current guest physical address to map.
  * @len:	   sanity check; the range being access must fit a single page.
@@ -1313,8 +1312,7 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
  * Callers in IN_GUEST_MODE may do so without locking, although they should
  * still hold a read lock on kvm->scru for the memslot checks.
  */
-bool kvm_gpc_check(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, gpa_t gpa,
-		   unsigned long len);
+bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len);
 
 /**
  * kvm_gpc_refresh - update a previously initialized cache.

virt/kvm/pfncache.c

@@ -76,10 +76,9 @@ void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, unsigned long start,
 	}
 }
 
-bool kvm_gpc_check(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, gpa_t gpa,
-		   unsigned long len)
+bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
 {
-	struct kvm_memslots *slots = kvm_memslots(kvm);
+	struct kvm_memslots *slots = kvm_memslots(gpc->kvm);
 
 	if (!gpc->active)
 		return false;