linux-kernel - [PATCH v2 11/22] KVM: x86: Fold retry_instruction() into x86_emulate

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Message-ID: <20240831001538.336683-12-seanjc@google.com>
Date: Fri, 30 Aug 2024 17:15:26 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yuan Yao <yuan.yao@...el.com>, Yuan Yao <yuan.yao@...ux.intel.com>
Subject: [PATCH v2 11/22] KVM: x86: Fold retry_instruction() into x86_emulate_instruction()

Now that retry_instruction() is reasonably tiny, fold it into its sole
caller, x86_emulate_instruction().  In addition to getting rid of the
absurdly confusing retry_instruction() name, handling the retry in
x86_emulate_instruction() pairs it back up with the code that resets
last_retry_{eip,address}.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 30 +++++++++---------------------
 1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7ddca8edf91b..c873a587769a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8920,26 +8920,6 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	return !(emulation_type & EMULTYPE_WRITE_PF_TO_SP);
 }
 
-static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
-			      gpa_t cr2_or_gpa,  int emulation_type)
-{
-	struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
-
-	/*
-	 * If the emulation is caused by #PF and it is non-page_table
-	 * writing instruction, it means the VM-EXIT is caused by shadow
-	 * page protected, we can zap the shadow page and retry this
-	 * instruction directly.
-	 */
-	if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
-		return false;
-
-	if (x86_page_table_writing_insn(ctxt))
-		return false;
-
-	return kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa);
-}
-
 static int complete_emulated_mmio(struct kvm_vcpu *vcpu);
 static int complete_emulated_pio(struct kvm_vcpu *vcpu);
 
@@ -9219,7 +9199,15 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 		return 1;
 	}
 
-	if (retry_instruction(ctxt, cr2_or_gpa, emulation_type))
+	/*
+	 * If emulation was caused by a write-protection #PF on a non-page_table
+	 * writing instruction, try to unprotect the gfn, i.e. zap shadow pages,
+	 * and retry the instruction, as the vCPU is likely no longer using the
+	 * gfn as a page table.
+	 */
+	if ((emulation_type & EMULTYPE_ALLOW_RETRY_PF) &&
+	    !x86_page_table_writing_insn(ctxt) &&
+	    kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa))
 		return 1;
 
 	/* this is needed for vmware backdoor interface to work since it
-- 
2.46.0.469.g59c65b2a67-goog