linux-kernel - [PATCH v8 056/103] KVM: x86/mmu: Let vcpu re-try when faulting page type conflict

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Date:   Sun,  7 Aug 2022 15:01:41 -0700
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>
Subject: [PATCH v8 056/103] KVM: x86/mmu: Let vcpu re-try when faulting page type conflict

From: Xiaoyao Li <xiaoyao.li@...el.com>

When it gets a private page fault on a shared page, or vice verse, let
vcpu retry and vcpu will keep faulting until other vcpu maps the gpa to
matched page type.

Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/mmu/mmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 27deaf44ee80..c9c27945ed44 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4230,6 +4230,10 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 			return RET_PF_EMULATE;
 	}
 
+	if (kvm_gfn_shared_mask(vcpu->kvm) &&
+	    (kvm_mem_is_private(vcpu->kvm, fault->gfn) != fault->is_private))
+		return RET_PF_RETRY;
+
 	async = false;
 	fault->pfn = __gfn_to_pfn_memslot(slot, fault->gfn, false, &async,
 					  fault->write, &fault->map_writable,
-- 
2.25.1