linux-kernel - [PATCH 6/9] KVM: SVM: Add support for static allocation of unified Page Encryption Bitmap.

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Date:   Mon, 30 Nov 2020 23:33:14 +0000
From:   Ashish Kalra <Ashish.Kalra@....com>
To:     pbonzini@...hat.com
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        rkrcmar@...hat.com, joro@...tes.org, bp@...e.de,
        thomas.lendacky@....com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, srutherford@...gle.com,
        brijesh.singh@....com, dovmurik@...ux.vnet.ibm.com, tobin@....com,
        jejb@...ux.ibm.com, frankeh@...ibm.com, dgilbert@...hat.com
Subject: [PATCH 6/9] KVM: SVM: Add support for static allocation of unified Page Encryption Bitmap.

From: Ashish Kalra <ashish.kalra@....com>

Add support for static allocation of the unified Page encryption bitmap by
extending kvm_arch_commit_memory_region() callack to add svm specific x86_ops
which can read the userspace provided memory region/memslots and calculate
the amount of guest RAM managed by the KVM and grow the bitmap based
on that information, i.e. the highest guest PA that is mapped by a memslot.

Signed-off-by: Ashish Kalra <ashish.kalra@....com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/svm/sev.c          | 35 +++++++++++++++++++++++++++++++++
 arch/x86/kvm/svm/svm.c          |  1 +
 arch/x86/kvm/svm/svm.h          |  1 +
 arch/x86/kvm/x86.c              |  5 +++++
 5 files changed, 43 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 352ebc576036..91fc22d793e8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1282,6 +1282,7 @@ struct kvm_x86_ops {
 
 	void (*migrate_timers)(struct kvm_vcpu *vcpu);
 	void (*msr_filter_changed)(struct kvm_vcpu *vcpu);
+	void (*commit_memory_region)(struct kvm *kvm, enum kvm_mr_change change);
 	int (*page_enc_status_hc)(struct kvm *kvm, unsigned long gpa,
 				  unsigned long sz, unsigned long mode);
 	int (*get_page_enc_bitmap)(struct kvm *kvm,
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9fe9fba34e68..37cf12cfbde6 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -957,6 +957,41 @@ static int sev_resize_page_enc_bitmap(struct kvm *kvm, unsigned long new_size)
 	return 0;
 }
 
+void svm_commit_memory_region(struct kvm *kvm, enum kvm_mr_change change)
+{
+	struct kvm_memslots *slots;
+	struct kvm_memory_slot *memslot;
+	gfn_t start, end = 0;
+
+	spin_lock(&kvm->mmu_lock);
+	if (change == KVM_MR_CREATE) {
+		slots = kvm_memslots(kvm);
+		kvm_for_each_memslot(memslot, slots) {
+			start = memslot->base_gfn;
+			end = memslot->base_gfn + memslot->npages;
+			/*
+			 * KVM memslots is a sorted list, starting with
+			 * the highest mapped guest PA, so pick the topmost
+			 * valid guest PA.
+			 */
+			if (memslot->npages)
+				break;
+		}
+	}
+	spin_unlock(&kvm->mmu_lock);
+
+	if (end) {
+		/*
+		 * NORE: This callback is invoked in vm ioctl
+		 * set_user_memory_region, hence we can use a
+		 * mutex here.
+		 */
+		mutex_lock(&kvm->lock);
+		sev_resize_page_enc_bitmap(kvm, end);
+		mutex_unlock(&kvm->lock);
+	}
+}
+
 int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
 				  unsigned long npages, unsigned long enc)
 {
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 6ebdf20773ea..7aa7858c8209 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4313,6 +4313,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
 	.msr_filter_changed = svm_msr_filter_changed,
 
+	.commit_memory_region = svm_commit_memory_region,
 	.page_enc_status_hc = svm_page_enc_status_hc,
 	.get_page_enc_bitmap = svm_get_page_enc_bitmap,
 	.set_page_enc_bitmap = svm_set_page_enc_bitmap,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 2268c0ab650b..5a4656bad681 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -415,6 +415,7 @@ int svm_page_enc_status_hc(struct kvm *kvm, unsigned long gpa,
                            unsigned long npages, unsigned long enc);
 int svm_get_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);
 int svm_set_page_enc_bitmap(struct kvm *kvm, struct kvm_page_enc_bitmap *bmap);
+void svm_commit_memory_region(struct kvm *kvm, enum kvm_mr_change change);
 
 extern struct kvm_x86_nested_ops svm_nested_ops;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3cf64a94004f..c1acbd397b50 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10717,6 +10717,11 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	/* Free the arrays associated with the old memslot. */
 	if (change == KVM_MR_MOVE)
 		kvm_arch_free_memslot(kvm, old);
+
+	if (change == KVM_MR_CREATE || change == KVM_MR_DELETE) {
+		if (kvm_x86_ops.commit_memory_region)
+			kvm_x86_ops.commit_memory_region(kvm, change);
+	}
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
-- 
2.17.1