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authorJan Kiszka <jan.kiszka@siemens.com>2008-12-15 13:52:10 +0100
committerAvi Kivity <avi@redhat.com>2009-03-24 11:02:49 +0200
commitd0bfb940ecabf0b44fb1fd80d8d60594e569e5ec (patch)
treeb5927d44937a54ec23d2a28d59db06a0262c0412 /arch/x86/kvm
parent8ab2d2e231062814bd89bba2d6d92563190aa2bb (diff)
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KVM: New guest debug interface
This rips out the support for KVM_DEBUG_GUEST and introduces a new IOCTL instead: KVM_SET_GUEST_DEBUG. The IOCTL payload consists of a generic part, controlling the "main switch" and the single-step feature. The arch specific part adds an x86 interface for intercepting both types of debug exceptions separately and re-injecting them when the host was not interested. Moveover, the foundation for guest debugging via debug registers is layed. To signal breakpoint events properly back to userland, an arch-specific data block is now returned along KVM_EXIT_DEBUG. For x86, the arch block contains the PC, the debug exception, and relevant debug registers to tell debug events properly apart. The availability of this new interface is signaled by KVM_CAP_SET_GUEST_DEBUG. Empty stubs for not yet supported archs are provided. Note that both SVM and VTX are supported, but only the latter was tested yet. Based on the experience with all those VTX corner case, I would be fairly surprised if SVM will work out of the box. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/svm.c50
-rw-r--r--arch/x86/kvm/vmx.c93
-rw-r--r--arch/x86/kvm/x86.c14
3 files changed, 92 insertions, 65 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0fbbde54eca..88d9062f454 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -968,9 +968,32 @@ static void svm_set_segment(struct kvm_vcpu *vcpu,
}
-static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_debug_guest *dbg)
+static int svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
{
- return -EOPNOTSUPP;
+ int old_debug = vcpu->guest_debug;
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ vcpu->guest_debug = dbg->control;
+
+ svm->vmcb->control.intercept_exceptions &=
+ ~((1 << DB_VECTOR) | (1 << BP_VECTOR));
+ if (vcpu->guest_debug & KVM_GUESTDBG_ENABLE) {
+ if (vcpu->guest_debug &
+ (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
+ svm->vmcb->control.intercept_exceptions |=
+ 1 << DB_VECTOR;
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP)
+ svm->vmcb->control.intercept_exceptions |=
+ 1 << BP_VECTOR;
+ } else
+ vcpu->guest_debug = 0;
+
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
+ svm->vmcb->save.rflags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
+ else if (old_debug & KVM_GUESTDBG_SINGLESTEP)
+ svm->vmcb->save.rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
+
+ return 0;
}
static int svm_get_irq(struct kvm_vcpu *vcpu)
@@ -1094,6 +1117,27 @@ static int pf_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
return kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code);
}
+static int db_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+ if (!(svm->vcpu.guest_debug &
+ (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))) {
+ kvm_queue_exception(&svm->vcpu, DB_VECTOR);
+ return 1;
+ }
+ kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ kvm_run->debug.arch.pc = svm->vmcb->save.cs.base + svm->vmcb->save.rip;
+ kvm_run->debug.arch.exception = DB_VECTOR;
+ return 0;
+}
+
+static int bp_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
+{
+ kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ kvm_run->debug.arch.pc = svm->vmcb->save.cs.base + svm->vmcb->save.rip;
+ kvm_run->debug.arch.exception = BP_VECTOR;
+ return 0;
+}
+
static int ud_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
{
int er;
@@ -2050,6 +2094,8 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm,
[SVM_EXIT_WRITE_DR3] = emulate_on_interception,
[SVM_EXIT_WRITE_DR5] = emulate_on_interception,
[SVM_EXIT_WRITE_DR7] = emulate_on_interception,
+ [SVM_EXIT_EXCP_BASE + DB_VECTOR] = db_interception,
+ [SVM_EXIT_EXCP_BASE + BP_VECTOR] = bp_interception,
[SVM_EXIT_EXCP_BASE + UD_VECTOR] = ud_interception,
[SVM_EXIT_EXCP_BASE + PF_VECTOR] = pf_interception,
[SVM_EXIT_EXCP_BASE + NM_VECTOR] = nm_interception,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1d974c1eaa7..f55690ddb3a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -480,8 +480,13 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
eb = (1u << PF_VECTOR) | (1u << UD_VECTOR);
if (!vcpu->fpu_active)
eb |= 1u << NM_VECTOR;
- if (vcpu->guest_debug.enabled)
- eb |= 1u << DB_VECTOR;
+ if (vcpu->guest_debug & KVM_GUESTDBG_ENABLE) {
+ if (vcpu->guest_debug &
+ (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
+ eb |= 1u << DB_VECTOR;
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP)
+ eb |= 1u << BP_VECTOR;
+ }
if (vcpu->arch.rmode.active)
eb = ~0;
if (vm_need_ept())
@@ -1003,40 +1008,23 @@ static void vmx_cache_reg(struct kvm_vcpu *vcpu, enum kvm_reg reg)
}
}
-static int set_guest_debug(struct kvm_vcpu *vcpu, struct kvm_debug_guest *dbg)
+static int set_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg)
{
- unsigned long dr7 = 0x400;
- int old_singlestep;
-
- old_singlestep = vcpu->guest_debug.singlestep;
-
- vcpu->guest_debug.enabled = dbg->enabled;
- if (vcpu->guest_debug.enabled) {
- int i;
-
- dr7 |= 0x200; /* exact */
- for (i = 0; i < 4; ++i) {
- if (!dbg->breakpoints[i].enabled)
- continue;
- vcpu->guest_debug.bp[i] = dbg->breakpoints[i].address;
- dr7 |= 2 << (i*2); /* global enable */
- dr7 |= 0 << (i*4+16); /* execution breakpoint */
- }
-
- vcpu->guest_debug.singlestep = dbg->singlestep;
- } else
- vcpu->guest_debug.singlestep = 0;
+ int old_debug = vcpu->guest_debug;
+ unsigned long flags;
- if (old_singlestep && !vcpu->guest_debug.singlestep) {
- unsigned long flags;
+ vcpu->guest_debug = dbg->control;
+ if (!(vcpu->guest_debug & KVM_GUESTDBG_ENABLE))
+ vcpu->guest_debug = 0;
- flags = vmcs_readl(GUEST_RFLAGS);
+ flags = vmcs_readl(GUEST_RFLAGS);
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
+ flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
+ else if (old_debug & KVM_GUESTDBG_SINGLESTEP)
flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
- vmcs_writel(GUEST_RFLAGS, flags);
- }
+ vmcs_writel(GUEST_RFLAGS, flags);
update_exception_bitmap(vcpu);
- vmcs_writel(GUEST_DR7, dr7);
return 0;
}
@@ -2540,24 +2528,6 @@ static int vmx_set_tss_addr(struct kvm *kvm, unsigned int addr)
return 0;
}
-static void kvm_guest_debug_pre(struct kvm_vcpu *vcpu)
-{
- struct kvm_guest_debug *dbg = &vcpu->guest_debug;
-
- set_debugreg(dbg->bp[0], 0);
- set_debugreg(dbg->bp[1], 1);
- set_debugreg(dbg->bp[2], 2);
- set_debugreg(dbg->bp[3], 3);
-
- if (dbg->singlestep) {
- unsigned long flags;
-
- flags = vmcs_readl(GUEST_RFLAGS);
- flags |= X86_EFLAGS_TF | X86_EFLAGS_RF;
- vmcs_writel(GUEST_RFLAGS, flags);
- }
-}
-
static int handle_rmode_exception(struct kvm_vcpu *vcpu,
int vec, u32 err_code)
{
@@ -2574,9 +2544,17 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu,
* the required debugging infrastructure rework.
*/
switch (vec) {
- case DE_VECTOR:
case DB_VECTOR:
+ if (vcpu->guest_debug &
+ (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP))
+ return 0;
+ kvm_queue_exception(vcpu, vec);
+ return 1;
case BP_VECTOR:
+ if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP)
+ return 0;
+ /* fall through */
+ case DE_VECTOR:
case OF_VECTOR:
case BR_VECTOR:
case UD_VECTOR:
@@ -2593,7 +2571,7 @@ static int handle_rmode_exception(struct kvm_vcpu *vcpu,
static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
- u32 intr_info, error_code;
+ u32 intr_info, ex_no, error_code;
unsigned long cr2, rip;
u32 vect_info;
enum emulation_result er;
@@ -2653,14 +2631,16 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
return 1;
}
- if ((intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK)) ==
- (INTR_TYPE_HARD_EXCEPTION | 1)) {
+ ex_no = intr_info & INTR_INFO_VECTOR_MASK;
+ if (ex_no == DB_VECTOR || ex_no == BP_VECTOR) {
kvm_run->exit_reason = KVM_EXIT_DEBUG;
- return 0;
+ kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
+ kvm_run->debug.arch.exception = ex_no;
+ } else {
+ kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
+ kvm_run->ex.exception = ex_no;
+ kvm_run->ex.error_code = error_code;
}
- kvm_run->exit_reason = KVM_EXIT_EXCEPTION;
- kvm_run->ex.exception = intr_info & INTR_INFO_VECTOR_MASK;
- kvm_run->ex.error_code = error_code;
return 0;
}
@@ -3600,7 +3580,6 @@ static struct kvm_x86_ops vmx_x86_ops = {
.vcpu_put = vmx_vcpu_put,
.set_guest_debug = set_guest_debug,
- .guest_debug_pre = kvm_guest_debug_pre,
.get_msr = vmx_get_msr,
.set_msr = vmx_set_msr,
.get_segment_base = vmx_get_segment_base,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b5e9932e0f6..e990d164b56 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3005,9 +3005,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
goto out;
}
- if (vcpu->guest_debug.enabled)
- kvm_x86_ops->guest_debug_pre(vcpu);
-
vcpu->guest_mode = 1;
/*
* Make sure that guest_mode assignment won't happen after
@@ -3218,7 +3215,7 @@ int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
/*
* Don't leak debug flags in case they were set for guest debugging
*/
- if (vcpu->guest_debug.enabled && vcpu->guest_debug.singlestep)
+ if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
regs->rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF);
vcpu_put(vcpu);
@@ -3837,8 +3834,8 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
return 0;
}
-int kvm_arch_vcpu_ioctl_debug_guest(struct kvm_vcpu *vcpu,
- struct kvm_debug_guest *dbg)
+int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
+ struct kvm_guest_debug *dbg)
{
int r;
@@ -3846,6 +3843,11 @@ int kvm_arch_vcpu_ioctl_debug_guest(struct kvm_vcpu *vcpu,
r = kvm_x86_ops->set_guest_debug(vcpu, dbg);
+ if (dbg->control & KVM_GUESTDBG_INJECT_DB)
+ kvm_queue_exception(vcpu, DB_VECTOR);
+ else if (dbg->control & KVM_GUESTDBG_INJECT_BP)
+ kvm_queue_exception(vcpu, BP_VECTOR);
+
vcpu_put(vcpu);
return r;