[PATCH v10 04/19] KVM: pfncache: add a mark-dirty helper

Paul Durrant
2023-12-04T15:01:23Z

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 | 11 +++++++++++
3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1983947b8965..09827c07be61 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3148,7 +3148,7 @@ 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 ea1523a7b83a..64dd616612ed 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1400,6 +1400,17 @@ 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)
+{
+ lockdep_assert_held(&gpc->lock);
+ 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