[PATCH v13 04/21] KVM: pfncache: add a mark-dirty helper

[Paul Durrant <paul@xen.org>]

From: Paul Durrant <pdurrant@amazon.com>

At the moment pages are marked dirty by open-coded calls to
mark_page_dirty_in_slot(), directly deferefencing the gpa and memslot
from the cache. After a subsequent patch these may not always be set
so add a helper now so that caller will protected from the need to know
about this detail.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
---
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org

v13:
 - s/kvm_gpc_mark_dirty/kvm_gpc_mark_dirty_in_slot
 - Add a check for a NULL memslot pointer

v8:
 - Make the helper a static inline.
---
 arch/x86/kvm/x86.c       |  2 +-
 arch/x86/kvm/xen.c       |  6 +++---
 include/linux/kvm_host.h | 13 +++++++++++++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b66c45e7f6f8..16269430006f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3151,7 +3151,7 @@ static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
 
 	guest_hv_clock->version = ++vcpu->hv_clock.version;
 
-	mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
+	kvm_gpc_mark_dirty_in_slot(gpc);
 	read_unlock_irqrestore(&gpc->lock, flags);
 
 	trace_kvm_pvclock_update(v->vcpu_id, &vcpu->hv_clock);
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index f3327508ae41..2d001a9c6378 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -453,11 +453,11 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
 	}
 
 	if (user_len2) {
-		mark_page_dirty_in_slot(v->kvm, gpc2->memslot, gpc2->gpa >> PAGE_SHIFT);
+		kvm_gpc_mark_dirty_in_slot(gpc2);
 		read_unlock(&gpc2->lock);
 	}
 
-	mark_page_dirty_in_slot(v->kvm, gpc1->memslot, gpc1->gpa >> PAGE_SHIFT);
+	kvm_gpc_mark_dirty_in_slot(gpc1);
 	read_unlock_irqrestore(&gpc1->lock, flags);
 }
 
@@ -565,7 +565,7 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
 		WRITE_ONCE(vi->evtchn_upcall_pending, 1);
 	}
 
-	mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
+	kvm_gpc_mark_dirty_in_slot(gpc);
 	read_unlock_irqrestore(&gpc->lock, flags);
 
 	/* For the per-vCPU lapic vector, deliver it as MSI. */
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bbfefd7e612f..5a27b4389d32 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1398,6 +1398,19 @@ int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, unsigned long len);
  */
 void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc);
 
+/**
+ * kvm_gpc_mark_dirty_in_slot - mark a cached guest page as dirty.
+ *
+ * @gpc:	   struct gfn_to_pfn_cache object.
+ */
+static inline void kvm_gpc_mark_dirty_in_slot(struct gfn_to_pfn_cache *gpc)
+{
+	lockdep_assert_held(&gpc->lock);
+	if (gpc->memslot)
+		mark_page_dirty_in_slot(gpc->kvm, gpc->memslot,
+					gpc->gpa >> PAGE_SHIFT);
+}
+
 void kvm_sigset_activate(struct kvm_vcpu *vcpu);
 void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
 
-- 
2.39.2