linux-kernel - [PATCH v2 2/5] x86: KVM: svm: avoid flooding logs when skip_emulated

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Date:   Tue,  6 Aug 2019 08:01:47 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Jim Mattson <jmattson@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [PATCH v2 2/5] x86: KVM: svm: avoid flooding logs when skip_emulated_instruction() fails

When we're unable to skip instruction with kvm_emulate_instruction() we
will not advance RIP and most likely the guest will get stuck as
consequitive attempts to execute the same instruction will likely result
in the same behavior.

As we're not supposed to see these messages under normal conditions, switch
to pr_err_once().

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Reviewed-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7e843b340490..80f576e05112 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -782,7 +782,8 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	if (!svm->next_rip) {
 		if (kvm_emulate_instruction(vcpu, EMULTYPE_SKIP) !=
 				EMULATE_DONE)
-			printk(KERN_DEBUG "%s: NOP\n", __func__);
+			pr_err_once("KVM: %s: unable to skip instruction\n",
+				    __func__);
 		return;
 	}
 	if (svm->next_rip - kvm_rip_read(vcpu) > MAX_INST_SIZE)
-- 
2.20.1