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Date: Mon, 4 Oct 2010 17:56:26 +0200
From: Gleb Natapov <gleb@...hat.com>
To: kvm@...r.kernel.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, avi@...hat.com,
mingo@...e.hu, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
hpa@...or.com, riel@...hat.com, cl@...ux-foundation.org,
mtosatti@...hat.com
Subject: [PATCH v6 04/12] Add memory slot versioning and use it to provide fast guest write interface
Keep track of memslots changes by keeping generation number in memslots
structure. Provide kvm_write_guest_cached() function that skips
gfn_to_hva() translation if memslots was not changed since previous
invocation.
Signed-off-by: Gleb Natapov <gleb@...hat.com>
---
include/linux/kvm_host.h | 7 +++++
include/linux/kvm_types.h | 7 +++++
virt/kvm/kvm_main.c | 57 +++++++++++++++++++++++++++++++++++++++++---
3 files changed, 67 insertions(+), 4 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a08614e..4dff9a1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -199,6 +199,7 @@ struct kvm_irq_routing_table {};
struct kvm_memslots {
int nmemslots;
+ u32 generation;
struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +
KVM_PRIVATE_MEM_SLOTS];
};
@@ -352,12 +353,18 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
int offset, int len);
int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
unsigned long len);
+int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned long len);
+int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ gpa_t gpa);
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);
int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn);
unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn);
void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
+void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
+ gfn_t gfn);
void kvm_vcpu_block(struct kvm_vcpu *vcpu);
void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu);
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 7ac0d4e..ee6eb71 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -67,4 +67,11 @@ struct kvm_lapic_irq {
u32 dest_id;
};
+struct gfn_to_hva_cache {
+ u32 generation;
+ gpa_t gpa;
+ unsigned long hva;
+ struct kvm_memory_slot *memslot;
+};
+
#endif /* __KVM_TYPES_H__ */
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index db58a1b..45ef50c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -687,6 +687,7 @@ skip_lpage:
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
if (mem->slot >= slots->nmemslots)
slots->nmemslots = mem->slot + 1;
+ slots->generation++;
slots->memslots[mem->slot].flags |= KVM_MEMSLOT_INVALID;
old_memslots = kvm->memslots;
@@ -723,6 +724,7 @@ skip_lpage:
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
if (mem->slot >= slots->nmemslots)
slots->nmemslots = mem->slot + 1;
+ slots->generation++;
/* actual memory is freed via old in kvm_free_physmem_slot below */
if (!npages) {
@@ -1247,6 +1249,47 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
return 0;
}
+int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ gpa_t gpa)
+{
+ struct kvm_memslots *slots = kvm_memslots(kvm);
+ int offset = offset_in_page(gpa);
+ gfn_t gfn = gpa >> PAGE_SHIFT;
+
+ ghc->gpa = gpa;
+ ghc->generation = slots->generation;
+ ghc->memslot = gfn_to_memslot(kvm, gfn);
+ ghc->hva = gfn_to_hva(kvm, gfn);
+ if (!kvm_is_error_hva(ghc->hva))
+ ghc->hva += offset;
+ else
+ return -EFAULT;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
+
+int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned long len)
+{
+ struct kvm_memslots *slots = kvm_memslots(kvm);
+ int r;
+
+ if (slots->generation != ghc->generation)
+ kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa);
+
+ if (kvm_is_error_hva(ghc->hva))
+ return -EFAULT;
+
+ r = copy_to_user((void __user *)ghc->hva, data, len);
+ if (r)
+ return -EFAULT;
+ mark_page_dirty_in_slot(kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_write_guest_cached);
+
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
{
return kvm_write_guest_page(kvm, gfn, empty_zero_page, offset, len);
@@ -1272,11 +1315,9 @@ int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
}
EXPORT_SYMBOL_GPL(kvm_clear_guest);
-void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
+void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
+ gfn_t gfn)
{
- struct kvm_memory_slot *memslot;
-
- memslot = gfn_to_memslot(kvm, gfn);
if (memslot && memslot->dirty_bitmap) {
unsigned long rel_gfn = gfn - memslot->base_gfn;
@@ -1284,6 +1325,14 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
}
}
+void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
+{
+ struct kvm_memory_slot *memslot;
+
+ memslot = gfn_to_memslot(kvm, gfn);
+ mark_page_dirty_in_slot(kvm, memslot, gfn);
+}
+
/*
* The vCPU has executed a HLT instruction with in-kernel mode enabled.
*/
--
1.7.1
--
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