Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "A new testcase for guest debugging (gdbstub) that exposed a bunch of
  bugs, mostly for AMD processors. And a few other x86 fixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Fix off-by-one error in kvm_vcpu_ioctl_x86_setup_mce
  KVM: x86: Fix pkru save/restore when guest CR4.PKE=0, move it to x86.c
  KVM: SVM: Disable AVIC before setting V_IRQ
  KVM: Introduce kvm_make_all_cpus_request_except()
  KVM: VMX: pass correct DR6 for GD userspace exit
  KVM: x86, SVM: isolate vcpu->arch.dr6 from vmcb->save.dr6
  KVM: SVM: keep DR6 synchronized with vcpu->arch.dr6
  KVM: nSVM: trap #DB and #BP to userspace if guest debugging is on
  KVM: selftests: Add KVM_SET_GUEST_DEBUG test
  KVM: X86: Fix single-step with KVM_SET_GUEST_DEBUG
  KVM: X86: Set RTM for DB_VECTOR too for KVM_EXIT_DEBUG
  KVM: x86: fix DR6 delivery for various cases of #DB injection
  KVM: X86: Declare KVM_CAP_SET_GUEST_DEBUG properly

1 files changed, 31 insertions, 8 deletions

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 90a1ca939627..9a2a62e5afeb 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -19,6 +19,7 @@
 #include <linux/kernel.h>
 
 #include <asm/msr-index.h>
+#include <asm/debugreg.h>
 
 #include "kvm_emulate.h"
 #include "trace.h"
@@ -267,7 +268,7 @@ void enter_svm_guest_mode(struct vcpu_svm *svm, u64 vmcb_gpa,
 	svm->vmcb->save.rsp = nested_vmcb->save.rsp;
 	svm->vmcb->save.rip = nested_vmcb->save.rip;
 	svm->vmcb->save.dr7 = nested_vmcb->save.dr7;
-	svm->vmcb->save.dr6 = nested_vmcb->save.dr6;
+	svm->vcpu.arch.dr6  = nested_vmcb->save.dr6;
 	svm->vmcb->save.cpl = nested_vmcb->save.cpl;
 
 	svm->nested.vmcb_msrpm = nested_vmcb->control.msrpm_base_pa & ~0x0fffULL;
@@ -482,7 +483,7 @@ int nested_svm_vmexit(struct vcpu_svm *svm)
 	nested_vmcb->save.rsp    = vmcb->save.rsp;
 	nested_vmcb->save.rax    = vmcb->save.rax;
 	nested_vmcb->save.dr7    = vmcb->save.dr7;
-	nested_vmcb->save.dr6    = vmcb->save.dr6;
+	nested_vmcb->save.dr6    = svm->vcpu.arch.dr6;
 	nested_vmcb->save.cpl    = vmcb->save.cpl;
 
 	nested_vmcb->control.int_ctl           = vmcb->control.int_ctl;
@@ -606,26 +607,45 @@ static int nested_svm_exit_handled_msr(struct vcpu_svm *svm)
 /* DB exceptions for our internal use must not cause vmexit */
 static int nested_svm_intercept_db(struct vcpu_svm *svm)
 {
-	unsigned long dr6;
+	unsigned long dr6 = svm->vmcb->save.dr6;
+
+	/* Always catch it and pass it to userspace if debugging.  */
+	if (svm->vcpu.guest_debug &
+	    (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
+		return NESTED_EXIT_HOST;
 
 	/* if we're not singlestepping, it's not ours */
 	if (!svm->nmi_singlestep)
-		return NESTED_EXIT_DONE;
+		goto reflected_db;
 
 	/* if it's not a singlestep exception, it's not ours */
-	if (kvm_get_dr(&svm->vcpu, 6, &dr6))
-		return NESTED_EXIT_DONE;
 	if (!(dr6 & DR6_BS))
-		return NESTED_EXIT_DONE;
+		goto reflected_db;
 
 	/* if the guest is singlestepping, it should get the vmexit */
 	if (svm->nmi_singlestep_guest_rflags & X86_EFLAGS_TF) {
 		disable_nmi_singlestep(svm);
-		return NESTED_EXIT_DONE;
+		goto reflected_db;
 	}
 
 	/* it's ours, the nested hypervisor must not see this one */
 	return NESTED_EXIT_HOST;
+
+reflected_db:
+	/*
+	 * Synchronize guest DR6 here just like in kvm_deliver_exception_payload;
+	 * it will be moved into the nested VMCB by nested_svm_vmexit.  Once
+	 * exceptions will be moved to svm_check_nested_events, all this stuff
+	 * will just go away and we could just return NESTED_EXIT_HOST
+	 * unconditionally.  db_interception will queue the exception, which
+	 * will be processed by svm_check_nested_events if a nested vmexit is
+	 * required, and we will just use kvm_deliver_exception_payload to copy
+	 * the payload to DR6 before vmexit.
+	 */
+	WARN_ON(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT);
+	svm->vcpu.arch.dr6 &= ~(DR_TRAP_BITS | DR6_RTM);
+	svm->vcpu.arch.dr6 |= dr6 & ~DR6_FIXED_1;
+	return NESTED_EXIT_DONE;
 }
 
 static int nested_svm_intercept_ioio(struct vcpu_svm *svm)
@@ -682,6 +702,9 @@ static int nested_svm_intercept(struct vcpu_svm *svm)
 		if (svm->nested.intercept_exceptions & excp_bits) {
 			if (exit_code == SVM_EXIT_EXCP_BASE + DB_VECTOR)
 				vmexit = nested_svm_intercept_db(svm);
+			else if (exit_code == SVM_EXIT_EXCP_BASE + BP_VECTOR &&
+				 svm->vcpu.guest_debug & KVM_GUESTDBG_USE_SW_BP)
+				vmexit = NESTED_EXIT_HOST;
 			else
 				vmexit = NESTED_EXIT_DONE;
 		}