linux-kernel - [PATCH v2 09/14] KVM: remove kvm_arch_gmem_prepare

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Message-ID: <20240726185157.72821-10-pbonzini@redhat.com>
Date: Fri, 26 Jul 2024 14:51:52 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: seanjc@...gle.com,
	michael.roth@....com
Subject: [PATCH v2 09/14] KVM: remove kvm_arch_gmem_prepare_needed()

It is enough to return 0 if a guest need not do any preparation.
This is in fact how sev_gmem_prepare() works for non-SNP guests,
and it extends naturally to Intel hosts: the x86 callback for
gmem_prepare is optional and returns 0 if not defined.

Reviewed-by: Michael Roth <michael.roth@....com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c       |  5 -----
 include/linux/kvm_host.h |  1 -
 virt/kvm/guest_memfd.c   | 13 +++----------
 3 files changed, 3 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4db18924b2f2..ef3d3511e4af 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -13645,11 +13645,6 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
 EXPORT_SYMBOL_GPL(kvm_arch_no_poll);
 
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-bool kvm_arch_gmem_prepare_needed(struct kvm *kvm)
-{
-	return kvm->arch.vm_type == KVM_X86_SNP_VM;
-}
-
 int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order)
 {
 	return kvm_x86_call(gmem_prepare)(kvm, pfn, gfn, max_order);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 344d90771844..45373d42f314 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2447,7 +2447,6 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm,
 
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
 int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_order);
-bool kvm_arch_gmem_prepare_needed(struct kvm *kvm);
 #endif
 
 /**
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 444ded162154..191fd42067c0 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -29,16 +29,9 @@ static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slo
 				    pgoff_t index, struct folio *folio)
 {
 #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE
-	kvm_pfn_t pfn;
-	gfn_t gfn;
-	int rc;
-
-	if (!kvm_arch_gmem_prepare_needed(kvm))
-		return 0;
-
-	pfn = folio_file_pfn(folio, index);
-	gfn = slot->base_gfn + index - slot->gmem.pgoff;
-	rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, folio_order(folio));
+	kvm_pfn_t pfn = folio_file_pfn(folio, index);
+	gfn_t gfn = slot->base_gfn + index - slot->gmem.pgoff;
+	int rc = kvm_arch_gmem_prepare(kvm, gfn, pfn, folio_order(folio));
 	if (rc) {
 		pr_warn_ratelimited("gmem: Failed to prepare folio for index %lx GFN %llx PFN %llx error %d.\n",
 				    index, gfn, pfn, rc);
-- 
2.43.0