linux-kernel - [PATCH v3 5/7] KVM: SVM: Handle vectoring error in check_emulate

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Message-ID: <20241217181458.68690-6-iorlov@amazon.com>
Date: Tue, 17 Dec 2024 18:14:56 +0000
From: Ivan Orlov <iorlov@...zon.com>
To: <bp@...en8.de>, <dave.hansen@...ux.intel.com>, <mingo@...hat.com>,
	<pbonzini@...hat.com>, <seanjc@...gle.com>, <shuah@...nel.org>,
	<tglx@...utronix.de>
CC: Ivan Orlov <iorlov@...zon.com>, <hpa@...or.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<x86@...nel.org>, <dwmw@...zon.co.uk>, <pdurrant@...zon.co.uk>,
	<jalliste@...zon.co.uk>
Subject: [PATCH v3 5/7] KVM: SVM: Handle vectoring error in check_emulate_instruction

Detect unhandleable vectoring in check_emulate_instruction to prevent
infinite loop on SVM and eliminate the difference in how intercepted #PF
during vectoring is handled on SVM and VMX.

Signed-off-by: Ivan Orlov <iorlov@...zon.com>
---
V1 -> V2:
- Detect the unhandleable vectoring error in svm_check_emulate_instruction
instead of handling it in the common MMU code (which is specific for
cached MMIO)
V2 -> V3:
- Use more generic function to check if emulation is allowed when
vectoring

 arch/x86/kvm/svm/svm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index dd15cc635655..e89c6fc2c4e6 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4802,6 +4802,12 @@ static int svm_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
 	bool smep, smap, is_user;
 	u64 error_code;
 
+	/* Check that emulation is possible during event vectoring */
+	if ((to_svm(vcpu)->vmcb->control.exit_int_info &
+	    SVM_EXITINTINFO_TYPE_MASK) &&
+	    !kvm_can_emulate_event_vectoring(emul_type))
+		return X86EMUL_UNHANDLEABLE_VECTORING;
+
 	/* Emulation is always possible when KVM has access to all guest state. */
 	if (!sev_guest(vcpu->kvm))
 		return X86EMUL_CONTINUE;
-- 
2.43.0