linux-kernel - [PATCH v2 3/4] KVM: x86: Drop superfluous check on direct MMU vs. WRITE_PF_TO

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Message-ID: <20240203002343.383056-4-seanjc@google.com>
Date: Fri,  2 Feb 2024 16:23:42 -0800
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, 
	Jim Mattson <jmattson@...gle.com>, Mingwei Zhang <mizhang@...gle.com>
Subject: [PATCH v2 3/4] KVM: x86: Drop superfluous check on direct MMU vs.
 WRITE_PF_TO_SP flag

Remove reexecute_instruction()'s final check on the MMU being direct, as
EMULTYPE_WRITE_PF_TO_SP is only ever set if the MMU is indirect, i.e. is a
shadow MMU.  Prior to commit 93c05d3ef252 ("KVM: x86: improve
reexecute_instruction"), the flag simply didn't exist (and KVM actually
returned "true" unconditionally for both types of MMUs).  I.e. the
explicit check for a direct MMU is simply leftover artifact from old code.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c502121b7bee..5fe94b2de1dc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8804,8 +8804,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	 * then zap the SPTE to unprotect the gfn, and then do it all over
 	 * again.  Report the error to userspace.
 	 */
-	return vcpu->arch.mmu->root_role.direct ||
-	       !(emulation_type & EMULTYPE_WRITE_PF_TO_SP);
+	return !(emulation_type & EMULTYPE_WRITE_PF_TO_SP);
 }
 
 static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
-- 
2.43.0.594.gd9cf4e227d-goog