diff mbox series

[v9,04/15] KVM: pfncache: add a mark-dirty helper

Message ID 20231122121822.1042-5-paul@xen.org (mailing list archive)
State New, archived
Headers show
Series KVM: xen: update shared_info and vcpu_info handling | expand

Commit Message

Paul Durrant Nov. 22, 2023, 12:18 p.m. UTC 
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

v8:
 - Make the helper a static inline.
---
 arch/x86/kvm/x86.c       |  2 +-
 arch/x86/kvm/xen.c       |  6 +++---
 include/linux/kvm_host.h | 10 ++++++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

Comments

David Woodhouse Nov. 22, 2023, 12:24 p.m. UTC | #1 
On Wed, 2023-11-22 at 12:18 +0000, Paul Durrant wrote:
> 
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1367,6 +1367,16 @@ 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.
> + */
> +static inline void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc)
> +{
> +       mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
> +}

This doesn't rescind my existing ack, but it's probably worth asserting
that gpc->lock is held here?
Paul Durrant Nov. 22, 2023, 1:04 p.m. UTC | #2 
On 22/11/2023 12:24, David Woodhouse wrote:
> On Wed, 2023-11-22 at 12:18 +0000, Paul Durrant wrote:
>>
>> --- a/include/linux/kvm_host.h
>> +++ b/include/linux/kvm_host.h
>> @@ -1367,6 +1367,16 @@ 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.
>> + */
>> +static inline void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc)
>> +{
>> +       mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
>> +}
> 
> This doesn't rescind my existing ack, but it's probably worth asserting
> that gpc->lock is held here?

Yes, a good idea. If a v10 is needed, I'll add it. Otherwise I can do it 
as an incremental patch.

   Paul
diff mbox series

Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2c924075f6f1..f4ebac198ff5 100644
--- 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 426306022c2f..41a7c03f7204 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(gpc2);
 		read_unlock(&gpc2->lock);
 	}
 
-	mark_page_dirty_in_slot(v->kvm, gpc1->memslot, gpc1->gpa >> PAGE_SHIFT);
+	kvm_gpc_mark_dirty(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(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 fb6c6109fdca..ae83caa99974 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1367,6 +1367,16 @@  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.
+ */
+static inline void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc)
+{
+	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);