KVM: Drop @gpa from exported gfn=>pfn cache check() and refresh() helpers

Drop the @gpa param from the exported check()+refresh() helpers and limit
changing the cache's GPA to the activate path.  All external users just
feed in gpc->gpa, i.e. this is a fancy nop.

Allowing users to change the GPA at check()+refresh() is dangerous as
those helpers explicitly allow concurrent calls, e.g. KVM could get into
a livelock scenario.  It's also unclear as to what the expected behavior
should be if multiple tasks attempt to refresh with different GPAs.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

2 files changed, 13 insertions, 15 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 490df3e997fa..006b445996a9 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3035,12 +3035,10 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
 	unsigned long flags;
 
 	read_lock_irqsave(&gpc->lock, flags);
-	while (!kvm_gpc_check(gpc, gpc->gpa,
-			      offset + sizeof(*guest_hv_clock))) {
+	while (!kvm_gpc_check(gpc, offset + sizeof(*guest_hv_clock))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 
-		if (kvm_gpc_refresh(gpc, gpc->gpa,
-				    offset + sizeof(*guest_hv_clock)))
+		if (kvm_gpc_refresh(gpc, offset + sizeof(*guest_hv_clock)))
 			return;
 
 		read_lock_irqsave(&gpc->lock, flags);
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index f50c88b1eaab..5208e05ca9a6 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -272,14 +272,14 @@ 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(gpc1, gpc1->gpa, user_len1)) {
+	while (!kvm_gpc_check(gpc1, user_len1)) {
 		read_unlock_irqrestore(&gpc1->lock, flags);
 
 		/* When invoked from kvm_sched_out() we cannot sleep */
 		if (atomic)
 			return;
 
-		if (kvm_gpc_refresh(gpc1, gpc1->gpa, user_len1))
+		if (kvm_gpc_refresh(gpc1, user_len1))
 			return;
 
 		read_lock_irqsave(&gpc1->lock, flags);
@@ -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(gpc2, gpc2->gpa, user_len2)) {
+		if (!kvm_gpc_check(gpc2, user_len2)) {
 			read_unlock(&gpc2->lock);
 			read_unlock_irqrestore(&gpc1->lock, flags);
 
@@ -488,10 +488,10 @@ 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(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
+	while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 
-		if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info)))
+		if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info)))
 			return;
 
 		read_lock_irqsave(&gpc->lock, flags);
@@ -551,7 +551,7 @@ 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(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
+	while (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
 		read_unlock_irqrestore(&gpc->lock, flags);
 
 		/*
@@ -565,7 +565,7 @@ int __kvm_xen_has_interrupt(struct kvm_vcpu *v)
 		if (in_atomic() || !task_is_running(current))
 			return 1;
 
-		if (kvm_gpc_refresh(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
+		if (kvm_gpc_refresh(gpc, sizeof(struct vcpu_info))) {
 			/*
 			 * If this failed, userspace has screwed up the
 			 * vcpu_info mapping. No interrupts for you.
@@ -1154,7 +1154,7 @@ 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(gpc, gpc->gpa, PAGE_SIZE))
+	if (!kvm_gpc_check(gpc, PAGE_SIZE))
 		goto out_rcu;
 
 	ret = false;
@@ -1576,7 +1576,7 @@ 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(gpc, gpc->gpa, PAGE_SIZE))
+	if (!kvm_gpc_check(gpc, PAGE_SIZE))
 		goto out_rcu;
 
 	if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode) {
@@ -1610,7 +1610,7 @@ 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(gpc, gpc->gpa, sizeof(struct vcpu_info))) {
+		if (!kvm_gpc_check(gpc, sizeof(struct vcpu_info))) {
 			/*
 			 * Could not access the vcpu_info. Set the bit in-kernel
 			 * and prod the vCPU to deliver it for itself.
@@ -1708,7 +1708,7 @@ static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm)
 			break;
 
 		idx = srcu_read_lock(&kvm->srcu);
-		rc = kvm_gpc_refresh(gpc, gpc->gpa, PAGE_SIZE);
+		rc = kvm_gpc_refresh(gpc, PAGE_SIZE);
 		srcu_read_unlock(&kvm->srcu, idx);
 	} while(!rc);