162 lines
5.1 KiB
Diff
162 lines
5.1 KiB
Diff
From: KarimAllah Ahmed <karahmed@amazon.de>
|
|
Date: Thu, 31 Jan 2019 21:24:34 +0100
|
|
Subject: [03/11] KVM: Introduce a new guest mapping API
|
|
Origin: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit?id=0125ed16a990014e27001f72fe75ad567da45f87
|
|
|
|
commit e45adf665a53df0db37f784ed87c6b57ddd81885 upstream.
|
|
|
|
In KVM, specially for nested guests, there is a dominant pattern of:
|
|
|
|
=> map guest memory -> do_something -> unmap guest memory
|
|
|
|
In addition to all this unnecessarily noise in the code due to boiler plate
|
|
code, most of the time the mapping function does not properly handle memory
|
|
that is not backed by "struct page". This new guest mapping API encapsulate
|
|
most of this boiler plate code and also handles guest memory that is not
|
|
backed by "struct page".
|
|
|
|
The current implementation of this API is using memremap for memory that is
|
|
not backed by a "struct page" which would lead to a huge slow-down if it
|
|
was used for high-frequency mapping operations. The API does not have any
|
|
effect on current setups where guest memory is backed by a "struct page".
|
|
Further patches are going to also introduce a pfn-cache which would
|
|
significantly improve the performance of the memremap case.
|
|
|
|
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
|
|
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
|
|
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
|
|
[bwh: Backported to 4.19 as dependency of commit 1eff70a9abd4
|
|
"x86/kvm: Introduce kvm_(un)map_gfn()"]
|
|
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
|
|
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
---
|
|
include/linux/kvm_host.h | 28 ++++++++++++++++++
|
|
virt/kvm/kvm_main.c | 64 ++++++++++++++++++++++++++++++++++++++++
|
|
2 files changed, 92 insertions(+)
|
|
|
|
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
|
|
index 0f99ecc01bc7..bef95dba14e8 100644
|
|
--- a/include/linux/kvm_host.h
|
|
+++ b/include/linux/kvm_host.h
|
|
@@ -206,6 +206,32 @@ enum {
|
|
READING_SHADOW_PAGE_TABLES,
|
|
};
|
|
|
|
+#define KVM_UNMAPPED_PAGE ((void *) 0x500 + POISON_POINTER_DELTA)
|
|
+
|
|
+struct kvm_host_map {
|
|
+ /*
|
|
+ * Only valid if the 'pfn' is managed by the host kernel (i.e. There is
|
|
+ * a 'struct page' for it. When using mem= kernel parameter some memory
|
|
+ * can be used as guest memory but they are not managed by host
|
|
+ * kernel).
|
|
+ * If 'pfn' is not managed by the host kernel, this field is
|
|
+ * initialized to KVM_UNMAPPED_PAGE.
|
|
+ */
|
|
+ struct page *page;
|
|
+ void *hva;
|
|
+ kvm_pfn_t pfn;
|
|
+ kvm_pfn_t gfn;
|
|
+};
|
|
+
|
|
+/*
|
|
+ * Used to check if the mapping is valid or not. Never use 'kvm_host_map'
|
|
+ * directly to check for that.
|
|
+ */
|
|
+static inline bool kvm_vcpu_mapped(struct kvm_host_map *map)
|
|
+{
|
|
+ return !!map->hva;
|
|
+}
|
|
+
|
|
/*
|
|
* Sometimes a large or cross-page mmio needs to be broken up into separate
|
|
* exits for userspace servicing.
|
|
@@ -711,7 +737,9 @@ struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
|
|
struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
|
|
kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
|
|
kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
|
|
+int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map);
|
|
struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
|
|
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty);
|
|
unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
|
|
unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
|
|
int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset,
|
|
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
|
|
index 4e499b78569b..ec1479abb29d 100644
|
|
--- a/virt/kvm/kvm_main.c
|
|
+++ b/virt/kvm/kvm_main.c
|
|
@@ -1705,6 +1705,70 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
|
|
}
|
|
EXPORT_SYMBOL_GPL(gfn_to_page);
|
|
|
|
+static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
|
|
+ struct kvm_host_map *map)
|
|
+{
|
|
+ kvm_pfn_t pfn;
|
|
+ void *hva = NULL;
|
|
+ struct page *page = KVM_UNMAPPED_PAGE;
|
|
+
|
|
+ if (!map)
|
|
+ return -EINVAL;
|
|
+
|
|
+ pfn = gfn_to_pfn_memslot(slot, gfn);
|
|
+ if (is_error_noslot_pfn(pfn))
|
|
+ return -EINVAL;
|
|
+
|
|
+ if (pfn_valid(pfn)) {
|
|
+ page = pfn_to_page(pfn);
|
|
+ hva = kmap(page);
|
|
+ } else {
|
|
+ hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
|
|
+ }
|
|
+
|
|
+ if (!hva)
|
|
+ return -EFAULT;
|
|
+
|
|
+ map->page = page;
|
|
+ map->hva = hva;
|
|
+ map->pfn = pfn;
|
|
+ map->gfn = gfn;
|
|
+
|
|
+ return 0;
|
|
+}
|
|
+
|
|
+int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
|
|
+{
|
|
+ return __kvm_map_gfn(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, map);
|
|
+}
|
|
+EXPORT_SYMBOL_GPL(kvm_vcpu_map);
|
|
+
|
|
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
|
|
+ bool dirty)
|
|
+{
|
|
+ if (!map)
|
|
+ return;
|
|
+
|
|
+ if (!map->hva)
|
|
+ return;
|
|
+
|
|
+ if (map->page)
|
|
+ kunmap(map->page);
|
|
+ else
|
|
+ memunmap(map->hva);
|
|
+
|
|
+ if (dirty) {
|
|
+ kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
|
|
+ kvm_release_pfn_dirty(map->pfn);
|
|
+ } else {
|
|
+ kvm_release_pfn_clean(map->pfn);
|
|
+ }
|
|
+
|
|
+ map->hva = NULL;
|
|
+ map->page = NULL;
|
|
+}
|
|
+EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
|
|
+
|
|
struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
|
|
{
|
|
kvm_pfn_t pfn;
|
|
--
|
|
2.27.0.rc0
|
|
|