linux-kernel - [PATCH 12/22] KVM: x86: Fold retry_instruction() into x86_emulate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240809190319.1710470-13-seanjc@google.com>
Date: Fri,  9 Aug 2024 12:03:09 -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, 
	Peter Gonda <pgonda@...gle.com>, Michael Roth <michael.roth@....com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Ackerly Tng <ackerleytng@...gle.com>
Subject: [PATCH 12/22] 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 7e90c3b888c2..771e67381fce 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8926,26 +8926,6 @@ 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);
 
@@ -9225,7 +9205,15 @@ 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
-- 
2.46.0.76.ge559c4bf1a-goog