linux-kernel - [PATCH] KVM: x86: Mark transfer type as X86_TRANSFER

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Date:   Wed, 12 Oct 2022 17:11:13 +0800
From:   "Hou Wenlong" <houwenlong.hwl@...group.com>
To:     kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86: Mark transfer type as X86_TRANSFER_RET when loading CS in iret emulation

When loading code segment descriptor in iret instruction emulation, the
checks are same as far return instruction emulation, so transfer type
should be X86_TRANSFER_RET in __load_segment_descriptor(). Although,
only iret in real mode is implemented now, and no checks are actually
needed for real mode, it would still be better to mark transfer type as
X86_TRANSFER_RET.

No functional change intended.

Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/emulate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3b27622d4642..5052eb480068 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2100,6 +2100,7 @@ static int emulate_iret_real(struct x86_emulate_ctxt *ctxt)
 			     X86_EFLAGS_FIXED;
 	unsigned long vm86_mask = X86_EFLAGS_VM | X86_EFLAGS_VIF |
 				  X86_EFLAGS_VIP;
+	u8 cpl = ctxt->ops->cpl(ctxt);
 
 	/* TODO: Add stack limit check */
 
@@ -2121,7 +2122,8 @@ static int emulate_iret_real(struct x86_emulate_ctxt *ctxt)
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 
-	rc = load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS);
+	rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl,
+				       X86_TRANSFER_RET, NULL);
 
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
-- 
2.31.1