KVM: pfncache: add a mark-dirty helper

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.

NOTE: Pages are now marked dirty while the cache lock is held. This is
      to ensure that gpa and memslot are mutually consistent.

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

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2c924075f6f112a594c0a4390bb7dcc2d7e8fabf..f4ebac198ff5c66d715d5b759daec50e230f35fa 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3145,7 +3145,7 @@ 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(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 e53fad915a626486936971757ca3ef61f5216d2c..41a7c03f7204c57e1640d0f9b9e8a40ec93f21bc 100644 (file)
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -452,14 +452,13 @@ static void kvm_xen_update_runstate_guest(struct kvm_vcpu *v, bool atomic)
                smp_wmb();
        }
 
-       if (user_len2)
+       if (user_len2) {
+               kvm_gpc_mark_dirty(gpc2);
                read_unlock(&gpc2->lock);
+       }
 
+       kvm_gpc_mark_dirty(gpc1);
        read_unlock_irqrestore(&gpc1->lock, flags);
-
-       mark_page_dirty_in_slot(v->kvm, gpc1->memslot, gpc1->gpa >> PAGE_SHIFT);
-       if (user_len2)
-               mark_page_dirty_in_slot(v->kvm, gpc2->memslot, gpc2->gpa >> PAGE_SHIFT);
 }
 
 void kvm_xen_update_runstate(struct kvm_vcpu *v, int state)
@@ -565,13 +564,13 @@ void kvm_xen_inject_pending_events(struct kvm_vcpu *v)
                             : "0" (evtchn_pending_sel32));
                WRITE_ONCE(vi->evtchn_upcall_pending, 1);
        }
+
+       kvm_gpc_mark_dirty(gpc);
        read_unlock_irqrestore(&gpc->lock, flags);
 
        /* For the per-vCPU lapic vector, deliver it as MSI. */
        if (v->arch.xen.upcall_vector)
                kvm_xen_inject_vcpu_vector(v);
-
-       mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
 }
 
 int __kvm_xen_has_interrupt(struct kvm_vcpu *v)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index fb6c6109fdcad69f81cd38edf52dce7dc3d7a4e9..c71e8fbccaaff96104fbbff98ab88ab7963f652d 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1367,6 +1367,13 @@ 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 - mark a cached page as dirty.
+ *
+ * @gpc:          struct gfn_to_pfn_cache object.
+ */
+void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc);
+
 void kvm_sigset_activate(struct kvm_vcpu *vcpu);
 void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);
 

diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
index 10842f1eeeae9baecbd937d186dfe6418c26f2f8..a8ac60599af69a26ff5f875ac0250b296bfcf5d3 100644 (file)
--- a/virt/kvm/pfncache.c
+++ b/virt/kvm/pfncache.c
@@ -390,6 +390,12 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
 }
 EXPORT_SYMBOL_GPL(kvm_gpc_activate);
 
+void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc)
+{
+       mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL_GPL(kvm_gpc_mark_dirty);
+
 void kvm_gpc_deactivate(struct gfn_to_pfn_cache *gpc)
 {
        struct kvm *kvm = gpc->kvm;