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[v4,08/20] KVM: x86/mmu: Pass memory caches to allocate SPs separately

Message ID 20220422210546.458943-9-dmatlack@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: Extend Eager Page Splitting to the shadow MMU | expand

Commit Message

David Matlack April 22, 2022, 9:05 p.m. UTC 
Refactor kvm_mmu_alloc_shadow_page() to receive the caches from which it
will allocate the various pieces of memory for shadow pages as a
parameter, rather than deriving them from the vcpu pointer. This will be
useful in a future commit where shadow pages are allocated during VM
ioctls for eager page splitting, and thus will use a different set of
caches.

Preemptively pull the caches out all the way to
kvm_mmu_get_shadow_page() since eager page splitting will not be calling
kvm_mmu_alloc_shadow_page() directly.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

Comments

Sean Christopherson May 5, 2022, 11 p.m. UTC | #1 
On Fri, Apr 22, 2022, David Matlack wrote:
> Refactor kvm_mmu_alloc_shadow_page() to receive the caches from which it
> will allocate the various pieces of memory for shadow pages as a
> parameter, rather than deriving them from the vcpu pointer. This will be
> useful in a future commit where shadow pages are allocated during VM
> ioctls for eager page splitting, and thus will use a different set of
> caches.
> 
> Preemptively pull the caches out all the way to
> kvm_mmu_get_shadow_page() since eager page splitting will not be calling
> kvm_mmu_alloc_shadow_page() directly.
> 
> No functional change intended.
> 
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---

...

>  static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
> +						      struct shadow_page_caches *caches,

Definitely work doing the "kvm" capture in an earlier patch, and doing the s/vcpu/kvm
here, the diff on top is tiny.  The shortlog/changelog would need minor tweaks, but
that's not a big deal.

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index da1c3cf91778..15784bab985f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2084,13 +2084,12 @@ struct shadow_page_caches {
        struct kvm_mmu_memory_cache *gfn_array_cache;
 };

-static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
                                                      struct shadow_page_caches *caches,
                                                      gfn_t gfn,
                                                      struct hlist_head *sp_list,
                                                      union kvm_mmu_page_role role)
 {
-       struct kvm *kvm = vcpu->kvm;
        struct kvm_mmu_page *sp;

        sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
@@ -2133,7 +2132,7 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
        sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
        if (!sp) {
                created = true;
-               sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
+               sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
        }

        trace_kvm_mmu_get_page(sp, created);
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Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4f894db88bbf..943595ed0ba1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2077,17 +2077,25 @@  static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
 	return sp;
 }
 
+/* Caches used when allocating a new shadow page. */
+struct shadow_page_caches {
+	struct kvm_mmu_memory_cache *page_header_cache;
+	struct kvm_mmu_memory_cache *shadow_page_cache;
+	struct kvm_mmu_memory_cache *gfn_array_cache;
+};
+
 static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+						      struct shadow_page_caches *caches,
 						      gfn_t gfn,
 						      struct hlist_head *sp_list,
 						      union kvm_mmu_page_role role)
 {
 	struct kvm_mmu_page *sp;
 
-	sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
-	sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+	sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
+	sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
 	if (!role.direct)
-		sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
+		sp->gfns = kvm_mmu_memory_cache_alloc(caches->gfn_array_cache);
 
 	set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
 
@@ -2110,9 +2118,10 @@  static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
 	return sp;
 }
 
-static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
-						    gfn_t gfn,
-						    union kvm_mmu_page_role role)
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+						      struct shadow_page_caches *caches,
+						      gfn_t gfn,
+						      union kvm_mmu_page_role role)
 {
 	struct hlist_head *sp_list;
 	struct kvm_mmu_page *sp;
@@ -2123,13 +2132,26 @@  static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
 	sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
 	if (!sp) {
 		created = true;
-		sp = kvm_mmu_alloc_shadow_page(vcpu, gfn, sp_list, role);
+		sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
 	}
 
 	trace_kvm_mmu_get_page(sp, created);
 	return sp;
 }
 
+static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+						    gfn_t gfn,
+						    union kvm_mmu_page_role role)
+{
+	struct shadow_page_caches caches = {
+		.page_header_cache = &vcpu->arch.mmu_page_header_cache,
+		.shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
+		.gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
+	};
+
+	return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+}
+
 static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
 {
 	struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep);