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Message-Id: <1501689810-20638-1-git-send-email-pbonzini@redhat.com>
Date:   Wed,  2 Aug 2017 18:03:30 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     rkcrmar@...hat.com, me@...ehuey.com
Subject: [PATCH] KVM: svm: support single stepping over emulated instructions

Use kvm_skip_emulated_instruction so that debug exceptions are
properly injected.  This fixes debug.flat on AMD machines.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/svm.c | 50 +++++++++++++++++++++-----------------------------
 arch/x86/kvm/x86.c |  1 +
 2 files changed, 22 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ba9891ac5c56..0c8b9cb715a3 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2245,6 +2245,7 @@ static int io_interception(struct vcpu_svm *svm)
 	u32 io_info = svm->vmcb->control.exit_info_1; /* address size bug? */
 	int size, in, string;
 	unsigned port;
+	int ret;
 
 	++svm->vcpu.stat.io_exits;
 	string = (io_info & SVM_IOIO_STR_MASK) != 0;
@@ -2255,10 +2256,10 @@ static int io_interception(struct vcpu_svm *svm)
 	port = io_info >> 16;
 	size = (io_info & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT;
 	svm->next_rip = svm->vmcb->control.exit_info_2;
-	skip_emulated_instruction(&svm->vcpu);
+	ret = kvm_skip_emulated_instruction(&svm->vcpu);
 
-	return in ? kvm_fast_pio_in(vcpu, size, port)
-		  : kvm_fast_pio_out(vcpu, size, port);
+	return (in ? kvm_fast_pio_in(vcpu, size, port)
+		   : kvm_fast_pio_out(vcpu, size, port)) && ret;
 }
 
 static int nmi_interception(struct vcpu_svm *svm)
@@ -3002,6 +3003,7 @@ static int vmload_interception(struct vcpu_svm *svm)
 {
 	struct vmcb *nested_vmcb;
 	struct page *page;
+	int ret;
 
 	if (nested_svm_check_permissions(svm))
 		return 1;
@@ -3011,18 +3013,18 @@ static int vmload_interception(struct vcpu_svm *svm)
 		return 1;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-	skip_emulated_instruction(&svm->vcpu);
+	ret = kvm_skip_emulated_instruction(&svm->vcpu);
 
 	nested_svm_vmloadsave(nested_vmcb, svm->vmcb);
 	nested_svm_unmap(page);
-
-	return 1;
+	return ret;
 }
 
 static int vmsave_interception(struct vcpu_svm *svm)
 {
 	struct vmcb *nested_vmcb;
 	struct page *page;
+	int ret;
 
 	if (nested_svm_check_permissions(svm))
 		return 1;
@@ -3032,12 +3034,11 @@ static int vmsave_interception(struct vcpu_svm *svm)
 		return 1;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-	skip_emulated_instruction(&svm->vcpu);
+	ret = kvm_skip_emulated_instruction(&svm->vcpu);
 
 	nested_svm_vmloadsave(svm->vmcb, nested_vmcb);
 	nested_svm_unmap(page);
-
-	return 1;
+	return ret;
 }
 
 static int vmrun_interception(struct vcpu_svm *svm)
@@ -3074,12 +3075,10 @@ static int stgi_interception(struct vcpu_svm *svm)
 		return 1;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-	skip_emulated_instruction(&svm->vcpu);
 	kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
-
 	enable_gif(svm);
 
-	return 1;
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int clgi_interception(struct vcpu_svm *svm)
@@ -3088,8 +3087,6 @@ static int clgi_interception(struct vcpu_svm *svm)
 		return 1;
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-	skip_emulated_instruction(&svm->vcpu);
-
 	disable_gif(svm);
 
 	/* After a CLGI no interrupts should come */
@@ -3099,7 +3096,7 @@ static int clgi_interception(struct vcpu_svm *svm)
 		mark_dirty(svm->vmcb, VMCB_INTR);
 	}
 
-	return 1;
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int invlpga_interception(struct vcpu_svm *svm)
@@ -3113,8 +3110,7 @@ static int invlpga_interception(struct vcpu_svm *svm)
 	kvm_mmu_invlpg(vcpu, kvm_register_read(&svm->vcpu, VCPU_REGS_RAX));
 
 	svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-	skip_emulated_instruction(&svm->vcpu);
-	return 1;
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int skinit_interception(struct vcpu_svm *svm)
@@ -3137,7 +3133,7 @@ static int xsetbv_interception(struct vcpu_svm *svm)
 
 	if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
 		svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
-		skip_emulated_instruction(&svm->vcpu);
+		return kvm_skip_emulated_instruction(&svm->vcpu);
 	}
 
 	return 1;
@@ -3233,8 +3229,7 @@ static int invlpg_interception(struct vcpu_svm *svm)
 		return emulate_instruction(&svm->vcpu, 0) == EMULATE_DONE;
 
 	kvm_mmu_invlpg(&svm->vcpu, svm->vmcb->control.exit_info_1);
-	skip_emulated_instruction(&svm->vcpu);
-	return 1;
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int emulate_on_interception(struct vcpu_svm *svm)
@@ -3384,9 +3379,7 @@ static int dr_interception(struct vcpu_svm *svm)
 		kvm_register_write(&svm->vcpu, reg, val);
 	}
 
-	skip_emulated_instruction(&svm->vcpu);
-
-	return 1;
+	return kvm_skip_emulated_instruction(&svm->vcpu);
 }
 
 static int cr8_write_interception(struct vcpu_svm *svm)
@@ -3509,6 +3502,7 @@ static int rdmsr_interception(struct vcpu_svm *svm)
 	if (svm_get_msr(&svm->vcpu, &msr_info)) {
 		trace_kvm_msr_read_ex(ecx);
 		kvm_inject_gp(&svm->vcpu, 0);
+		return 1;
 	} else {
 		trace_kvm_msr_read(ecx, msr_info.data);
 
@@ -3517,9 +3511,8 @@ static int rdmsr_interception(struct vcpu_svm *svm)
 		kvm_register_write(&svm->vcpu, VCPU_REGS_RDX,
 				   msr_info.data >> 32);
 		svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
-		skip_emulated_instruction(&svm->vcpu);
+		return kvm_skip_emulated_instruction(&svm->vcpu);
 	}
-	return 1;
 }
 
 static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 data)
@@ -3645,11 +3638,11 @@ static int wrmsr_interception(struct vcpu_svm *svm)
 	if (kvm_set_msr(&svm->vcpu, &msr)) {
 		trace_kvm_msr_write_ex(ecx, data);
 		kvm_inject_gp(&svm->vcpu, 0);
+		return 1;
 	} else {
 		trace_kvm_msr_write(ecx, data);
-		skip_emulated_instruction(&svm->vcpu);
+		return kvm_skip_emulated_instruction(&svm->vcpu);
 	}
-	return 1;
 }
 
 static int msr_interception(struct vcpu_svm *svm)
@@ -3678,8 +3671,7 @@ static int pause_interception(struct vcpu_svm *svm)
 
 static int nop_interception(struct vcpu_svm *svm)
 {
-	skip_emulated_instruction(&(svm->vcpu));
-	return 1;
+	return kvm_skip_emulated_instruction(&(svm->vcpu));
 }
 
 static int monitor_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0e846f0cb83b..931ba449456e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5548,6 +5548,7 @@ static void kvm_vcpu_do_singlestep(struct kvm_vcpu *vcpu, int *r)
 		 */
 		vcpu->arch.dr6 &= ~15;
 		vcpu->arch.dr6 |= DR6_BS | DR6_RTM;
+		kvm_update_dr6(vcpu);
 		kvm_queue_exception(vcpu, DB_VECTOR);
 	}
 }
-- 
1.8.3.1

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