linux-kernel - [PATCH v3 2/2] KVM: X86: Kill off ctxt->ud

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Message-Id: <1622091679-31683-2-git-send-email-wanpengli@tencent.com>
Date:   Wed, 26 May 2021 22:01:19 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH v3 2/2] KVM: X86: Kill off ctxt->ud

From: Wanpeng Li <wanpengli@...cent.com>

ctxt->ud is consumed only by x86_decode_insn(), we can kill it off by passing
emulation_type to x86_decode_insn() and dropping ctxt->ud altogether. Tracking 
that info in ctxt for literally one call is silly.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/emulate.c     | 5 +++--
 arch/x86/kvm/kvm_emulate.h | 3 +--
 arch/x86/kvm/x86.c         | 4 +---
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8a0ccdb..5e5de05 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5111,7 +5111,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
 	return rc;
 }
 
-int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
+int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len, int emulation_type)
 {
 	int rc = X86EMUL_CONTINUE;
 	int mode = ctxt->mode;
@@ -5322,7 +5322,8 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
 
 	ctxt->execute = opcode.u.execute;
 
-	if (unlikely(ctxt->ud) && likely(!(ctxt->d & EmulateOnUD)))
+	if (unlikely(emulation_type & EMULTYPE_TRAP_UD) &&
+	    likely(!(ctxt->d & EmulateOnUD)))
 		return EMULATION_FAILED;
 
 	if (unlikely(ctxt->d &
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index f016838..3e870bf 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -314,7 +314,6 @@ struct x86_emulate_ctxt {
 	int interruptibility;
 
 	bool perm_ok; /* do not check permissions if true */
-	bool ud;	/* inject an #UD if host doesn't support insn */
 	bool tf;	/* TF value before instruction (after for syscall/sysret) */
 
 	bool have_exception;
@@ -491,7 +490,7 @@ enum x86_intercept {
 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT64
 #endif
 
-int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len);
+int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len, int emulation_type);
 bool x86_page_table_writing_insn(struct x86_emulate_ctxt *ctxt);
 #define EMULATION_FAILED -1
 #define EMULATION_OK 0
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ae47b19..d752345 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7231,8 +7231,6 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
 	ctxt->exception.vector = -1;
 	ctxt->perm_ok = false;
 
-	ctxt->ud = emulation_type & EMULTYPE_TRAP_UD;
-
 	init_decode_cache(ctxt);
 	vcpu->arch.emulate_regs_need_sync_from_vcpu = false;
 }
@@ -7568,7 +7566,7 @@ int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type,
 	    kvm_vcpu_check_breakpoint(vcpu, &r))
 		return r;
 
-	r = x86_decode_insn(ctxt, insn, insn_len);
+	r = x86_decode_insn(ctxt, insn, insn_len, emulation_type);
 
 	trace_kvm_emulate_insn_start(vcpu);
 	++vcpu->stat.insn_emulation;
-- 
2.7.4