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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RESEND PATCH 09/13] KVM: x86: Exit to userspace on emulation skip failure
Date: Thu, 22 Aug 2019 18:07:05 -0700	[thread overview]
Message-ID: <20190823010709.24879-10-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20190823010709.24879-1-sean.j.christopherson@intel.com>

Kill a few birds with one stone by forcing an exit to userspace on skip
emulation failure.  This removes a reference to EMULATE_FAIL, fixes a
bug in handle_ept_misconfig() where it would exit to userspace without
setting run->exit_reason, and fixes a theoretical bug in SVM's
task_switch_interception() where it would overwrite run->exit_reason on
a return of EMULATE_USER_EXIT.

Note, this technically doesn't fully fix task_switch_interception()
as it now incorrectly handles EMULATE_FAIL, but in practice there is no
bug as EMULATE_FAIL will never be returned for EMULTYPE_SKIP.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/svm.c | 4 ++--
 arch/x86/kvm/x86.c | 9 +++++++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 97562c2c8b7b..c8e3bef2d586 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3881,8 +3881,8 @@ static int task_switch_interception(struct vcpu_svm *svm)
 	    int_type == SVM_EXITINTINFO_TYPE_SOFT ||
 	    (int_type == SVM_EXITINTINFO_TYPE_EXEPT &&
 	     (int_vec == OF_VECTOR || int_vec == BP_VECTOR))) {
-		if (skip_emulated_instruction(&svm->vcpu) != EMULATE_DONE)
-			goto fail;
+		if (skip_emulated_instruction(&svm->vcpu) == EMULATE_USER_EXIT)
+			return 0;
 	}
 
 	if (int_type != SVM_EXITINTINFO_TYPE_SOFT)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bff3320aa78e..1a886ec6957d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6209,6 +6209,13 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
 		return EMULATE_DONE;
 	}
 
+	if (emulation_type & EMULTYPE_SKIP) {
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+		vcpu->run->internal.ndata = 0;
+		return EMULATE_USER_EXIT;
+	}
+
 	kvm_queue_exception(vcpu, UD_VECTOR);
 
 	if (!is_guest_mode(vcpu) && kvm_x86_ops->get_cpl(vcpu) == 0) {
@@ -6536,8 +6543,6 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 				return EMULATE_DONE;
 			if (ctxt->have_exception && inject_emulated_exception(vcpu))
 				return EMULATE_DONE;
-			if (emulation_type & EMULTYPE_SKIP)
-				return EMULATE_FAIL;
 			return handle_emulation_failure(vcpu, emulation_type);
 		}
 	}
-- 
2.22.0


  parent reply	other threads:[~2019-08-23  1:08 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-23  1:06 [RESEND PATCH 00/13] KVM: x86: Remove emulation_result enums Sean Christopherson
2019-08-23  1:06 ` [RESEND PATCH 01/13] KVM: x86: Relocate MMIO exit stats counting Sean Christopherson
2019-08-23  9:15   ` Vitaly Kuznetsov
2019-08-23 14:37     ` Sean Christopherson
2019-08-23  1:06 ` [RESEND PATCH 02/13] KVM: x86: Clean up handle_emulation_failure() Sean Christopherson
2019-08-23  9:23   ` Vitaly Kuznetsov
2019-08-23 12:58     ` Liran Alon
2019-08-23  1:06 ` [RESEND PATCH 03/13] KVM: x86: Refactor kvm_vcpu_do_singlestep() to remove out param Sean Christopherson
2019-08-23  9:32   ` Vitaly Kuznetsov
2019-08-23 13:05   ` Liran Alon
2019-08-23  1:07 ` [RESEND PATCH 04/13] KVM: x86: Drop EMULTYPE_NO_UD_ON_FAIL as a standalone type Sean Christopherson
2019-08-23  9:34   ` Vitaly Kuznetsov
2019-08-23 13:21   ` Liran Alon
2019-08-23 13:32     ` Liran Alon
2019-08-23 21:55       ` Sean Christopherson
2019-08-23  1:07 ` [RESEND PATCH 05/13] KVM: x86: Don't attempt VMWare emulation on #GP with non-zero error code Sean Christopherson
2019-08-23 11:51   ` Vitaly Kuznetsov
2019-08-23 13:23   ` Liran Alon
2019-08-23  1:07 ` [RESEND PATCH 06/13] KVM: x86: Move #GP injection for VMware into x86_emulate_instruction() Sean Christopherson
2019-08-23 12:27   ` Vitaly Kuznetsov
2019-08-23 13:30   ` Liran Alon
2019-08-23  1:07 ` [RESEND PATCH 07/13] KVM: x86: Add explicit flag for forced emulation on #UD Sean Christopherson
2019-08-23 13:47   ` Liran Alon
2019-08-23 14:44     ` Sean Christopherson
2019-08-23 15:31       ` Liran Alon
2019-08-23  1:07 ` [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code Sean Christopherson
2019-08-23 13:48   ` Liran Alon
2019-08-27 20:22     ` Sean Christopherson
2019-08-23  1:07 ` Sean Christopherson [this message]
2019-08-23  1:07 ` [RESEND PATCH 10/13] KVM: x86: Handle emulation failure directly in kvm_task_switch() Sean Christopherson
2019-08-23  1:07 ` [RESEND PATCH 11/13] KVM: x86: Move triple fault request into RM int injection Sean Christopherson
2019-08-23  1:07 ` [RESEND PATCH 12/13] KVM: VMX: Remove EMULATE_FAIL handling in handle_invalid_guest_state() Sean Christopherson
2019-08-23  1:07 ` [RESEND PATCH 13/13] KVM: x86: Remove emulation_result enums, EMULATE_{DONE,FAIL,USER_EXIT} Sean Christopherson

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