linux-kernel - [PATCH 14/18] KVM: x86/mmu: Init memslot if memory attributes available

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Message-ID: <20240609154945.55332-15-nsaenz@amazon.com>
Date: Sun, 9 Jun 2024 15:49:43 +0000
From: Nicolas Saenz Julienne <nsaenz@...zon.com>
To: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC: <pbonzini@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
	<linux-doc@...r.kernel.org>, <linux-hyperv@...r.kernel.org>,
	<linux-arch@...r.kernel.org>, <linux-trace-kernel@...r.kernel.org>,
	<graf@...zon.de>, <dwmw2@...radead.org>, <paul@...zon.com>,
	<nsaenz@...zon.com>, <mlevitsk@...hat.com>, <jgowans@...zon.com>,
	<corbet@....net>, <decui@...rosoft.com>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, <amoorthy@...gle.com>
Subject: [PATCH 14/18] KVM: x86/mmu: Init memslot if memory attributes available

Systems that lack private memory support are about to start using memory
attributes. So query if the memory attributes xarray is empty in order
to decide whether it's necessary to init the hugepage information when
installing a new memslot.

Signed-off-by: Nicolas Saenz Julienne <nsaenz@...zon.com>
---
 arch/x86/kvm/mmu/mmu.c   | 2 +-
 include/linux/kvm_host.h | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d56c04fbdc66b..91edd873dcdbc 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -7487,7 +7487,7 @@ void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm,
 {
 	int level;
 
-	if (!kvm_arch_has_private_mem(kvm))
+	if (!kvm_memory_attributes_in_use(kvm))
 		return;
 
 	for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 4fa16c4772269..9250bf1c4db15 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2424,12 +2424,21 @@ bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm,
 bool kvm_arch_post_set_memory_attributes(struct kvm *kvm,
 					 struct kvm_gfn_range *range);
 
+static inline bool kvm_memory_attributes_in_use(struct kvm *kvm)
+{
+	return !xa_empty(&kvm->mem_attr_array);
+}
+
 static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 {
 	return IS_ENABLED(CONFIG_KVM_PRIVATE_MEM) &&
 	       kvm_get_memory_attributes(kvm, gfn) & KVM_MEMORY_ATTRIBUTE_PRIVATE;
 }
 #else
+static inline bool kvm_memory_attributes_in_use(struct kvm *kvm)
+{
+	return false;
+}
 static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn)
 {
 	return false;
-- 
2.40.1