linux-kernel - [PATCH v2 04/11] KVM: SVM: Stuff next_rip on emulated INT3 injection if NRIPS is supported

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Date:   Sat, 23 Apr 2022 02:14:04 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     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>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>,
        "Maciej S . Szmigiero" <maciej.szmigiero@...cle.com>
Subject: [PATCH v2 04/11] KVM: SVM: Stuff next_rip on emulated INT3 injection
 if NRIPS is supported

If NRIPS is supported in hardware but disabled in KVM, set next_rip to
the next RIP when advancing RIP as part of emulating INT3 injection.
There is no flag to tell the CPU that KVM isn't using next_rip, and so
leaving next_rip is left as is will result in the CPU pushing garbage
onto the stack when vectoring the injected event.

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
Fixes: 66b7138f9136 ("KVM: SVM: Emulate nRIP feature when reinjecting INT3")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 82175a13c668..14bc4e87437b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -392,6 +392,10 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu)
 		 */
 		(void)svm_skip_emulated_instruction(vcpu);
 		rip = kvm_rip_read(vcpu);
+
+		if (boot_cpu_has(X86_FEATURE_NRIPS))
+			svm->vmcb->control.next_rip = rip;
+
 		svm->int3_rip = rip + svm->vmcb->save.cs.base;
 		svm->int3_injected = rip - old_rip;
 	}
@@ -3703,7 +3707,7 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu)
 	/*
 	 * If NextRIP isn't enabled, KVM must manually advance RIP prior to
 	 * injecting the soft exception/interrupt.  That advancement needs to
-	 * be unwound if vectoring didn't complete.  Note, the _new_ event may
+	 * be unwound if vectoring didn't complete.  Note, the new event may
 	 * not be the injected event, e.g. if KVM injected an INTn, the INTn
 	 * hit a #NP in the guest, and the #NP encountered a #PF, the #NP will
 	 * be the reported vectored event, but RIP still needs to be unwound.
-- 
2.36.0.rc2.479.g8af0fa9b8e-goog