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>
diff --git a/arch/ia64/include/asm/kvm.h b/arch/ia64/include/asm/kvm.h
index bfa86b6..be3fdb8 100644
--- a/arch/ia64/include/asm/kvm.h
+++ b/arch/ia64/include/asm/kvm.h
@@ -214,4 +214,11 @@
struct kvm_fpu {
};
+struct kvm_debug_exit_arch {
+};
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+};
+
#endif
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 28f9820..de47467 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1303,8 +1303,8 @@
return -EINVAL;
}
-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)
{
return -EINVAL;
}
diff --git a/arch/powerpc/include/asm/kvm.h b/arch/powerpc/include/asm/kvm.h
index f993e41..755f1b1 100644
--- a/arch/powerpc/include/asm/kvm.h
+++ b/arch/powerpc/include/asm/kvm.h
@@ -52,4 +52,11 @@
__u64 fpr[32];
};
+struct kvm_debug_exit_arch {
+};
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+};
+
#endif /* __LINUX_KVM_POWERPC_H */
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 5f81256..7c2ad40 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -240,8 +240,8 @@
kvmppc_core_vcpu_put(vcpu);
}
-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 i;
diff --git a/arch/s390/include/asm/kvm.h b/arch/s390/include/asm/kvm.h
index e1f5465..0b2f829 100644
--- a/arch/s390/include/asm/kvm.h
+++ b/arch/s390/include/asm/kvm.h
@@ -42,4 +42,11 @@
__u64 fprs[16];
};
+struct kvm_debug_exit_arch {
+};
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+};
+
#endif
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 0d33893..cbfe91e 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -422,8 +422,8 @@
return -EINVAL; /* not implemented yet */
}
-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)
{
return -EINVAL; /* not implemented yet */
}
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 886c940..32eb96c 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -212,6 +212,24 @@
__s64 count_load_time;
};
+struct kvm_debug_exit_arch {
+ __u32 exception;
+ __u32 pad;
+ __u64 pc;
+ __u64 dr6;
+ __u64 dr7;
+};
+
+#define KVM_GUESTDBG_USE_SW_BP 0x00010000
+#define KVM_GUESTDBG_USE_HW_BP 0x00020000
+#define KVM_GUESTDBG_INJECT_DB 0x00040000
+#define KVM_GUESTDBG_INJECT_BP 0x00080000
+
+/* for KVM_SET_GUEST_DEBUG */
+struct kvm_guest_debug_arch {
+ __u64 debugreg[8];
+};
+
struct kvm_pit_state {
struct kvm_pit_channel_state channels[3];
};
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5377930..c430cd580 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -135,12 +135,6 @@
#define KVM_NR_MEM_OBJS 40
-struct kvm_guest_debug {
- int enabled;
- unsigned long bp[4];
- int singlestep;
-};
-
/*
* We don't want allocation failures within the mmu code, so we preallocate
* enough memory for a single page fault in a cache.
@@ -448,8 +442,7 @@
void (*vcpu_put)(struct kvm_vcpu *vcpu);
int (*set_guest_debug)(struct kvm_vcpu *vcpu,
- struct kvm_debug_guest *dbg);
- void (*guest_debug_pre)(struct kvm_vcpu *vcpu);
+ struct kvm_guest_debug *dbg);
int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
u64 (*get_segment_base)(struct kvm_vcpu *vcpu, int seg);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 0fbbde5..88d9062 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -968,9 +968,32 @@
}
-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 @@
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 @@
[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 1d974c1..f55690d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -480,8 +480,13 @@
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 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;
+ int old_debug = vcpu->guest_debug;
+ unsigned long flags;
- old_singlestep = vcpu->guest_debug.singlestep;
+ vcpu->guest_debug = dbg->control;
+ if (!(vcpu->guest_debug & KVM_GUESTDBG_ENABLE))
+ vcpu->guest_debug = 0;
- 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;
-
- if (old_singlestep && !vcpu->guest_debug.singlestep) {
- unsigned long flags;
-
- 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 @@
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 @@
* 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_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 @@
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 @@
.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 b5e9932..e990d16 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3005,9 +3005,6 @@
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 @@
/*
* 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 @@
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 @@
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;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 0424326f..429a2ce 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -126,6 +126,7 @@
__u64 data_offset; /* relative to kvm_run start */
} io;
struct {
+ struct kvm_debug_exit_arch arch;
} debug;
/* KVM_EXIT_MMIO */
struct {
@@ -217,21 +218,6 @@
__u32 irq;
};
-struct kvm_breakpoint {
- __u32 enabled;
- __u32 padding;
- __u64 address;
-};
-
-/* for KVM_DEBUG_GUEST */
-struct kvm_debug_guest {
- /* int */
- __u32 enabled;
- __u32 pad;
- struct kvm_breakpoint breakpoints[4];
- __u32 singlestep;
-};
-
/* for KVM_GET_DIRTY_LOG */
struct kvm_dirty_log {
__u32 slot;
@@ -292,6 +278,17 @@
__u64 parm64;
};
+/* for KVM_SET_GUEST_DEBUG */
+
+#define KVM_GUESTDBG_ENABLE 0x00000001
+#define KVM_GUESTDBG_SINGLESTEP 0x00000002
+
+struct kvm_guest_debug {
+ __u32 control;
+ __u32 pad;
+ struct kvm_guest_debug_arch arch;
+};
+
#define KVM_TRC_SHIFT 16
/*
* kvm trace categories
@@ -396,6 +393,7 @@
#ifdef __KVM_HAVE_USER_NMI
#define KVM_CAP_USER_NMI 22
#endif
+#define KVM_CAP_SET_GUEST_DEBUG 23
/*
* ioctls for VM fds
@@ -440,7 +438,8 @@
#define KVM_SET_SREGS _IOW(KVMIO, 0x84, struct kvm_sregs)
#define KVM_TRANSLATE _IOWR(KVMIO, 0x85, struct kvm_translation)
#define KVM_INTERRUPT _IOW(KVMIO, 0x86, struct kvm_interrupt)
-#define KVM_DEBUG_GUEST _IOW(KVMIO, 0x87, struct kvm_debug_guest)
+/* KVM_DEBUG_GUEST is no longer supported, use KVM_SET_GUEST_DEBUG instead */
+#define KVM_DEBUG_GUEST __KVM_DEPRECATED_DEBUG_GUEST
#define KVM_GET_MSRS _IOWR(KVMIO, 0x88, struct kvm_msrs)
#define KVM_SET_MSRS _IOW(KVMIO, 0x89, struct kvm_msrs)
#define KVM_SET_CPUID _IOW(KVMIO, 0x8a, struct kvm_cpuid)
@@ -469,6 +468,26 @@
#define KVM_SET_MP_STATE _IOW(KVMIO, 0x99, struct kvm_mp_state)
/* Available with KVM_CAP_NMI */
#define KVM_NMI _IO(KVMIO, 0x9a)
+/* Available with KVM_CAP_SET_GUEST_DEBUG */
+#define KVM_SET_GUEST_DEBUG _IOW(KVMIO, 0x9b, struct kvm_guest_debug)
+
+/*
+ * Deprecated interfaces
+ */
+struct kvm_breakpoint {
+ __u32 enabled;
+ __u32 padding;
+ __u64 address;
+};
+
+struct kvm_debug_guest {
+ __u32 enabled;
+ __u32 pad;
+ struct kvm_breakpoint breakpoints[4];
+ __u32 singlestep;
+};
+
+#define __KVM_DEPRECATED_DEBUG_GUEST _IOW(KVMIO, 0x87, struct kvm_debug_guest)
#define KVM_TRC_INJ_VIRQ (KVM_TRC_HANDLER + 0x02)
#define KVM_TRC_REDELIVER_EVT (KVM_TRC_HANDLER + 0x03)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index bf6f703..e92212f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -73,7 +73,7 @@
struct kvm_run *run;
int guest_mode;
unsigned long requests;
- struct kvm_guest_debug guest_debug;
+ unsigned long guest_debug;
int fpu_active;
int guest_fpu_loaded;
wait_queue_head_t wq;
@@ -255,8 +255,8 @@
struct kvm_mp_state *mp_state);
int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
struct kvm_mp_state *mp_state);
-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 kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run);
int kvm_arch_init(void *opaque);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 29a667c..f83ef9c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1755,13 +1755,13 @@
r = 0;
break;
}
- case KVM_DEBUG_GUEST: {
- struct kvm_debug_guest dbg;
+ case KVM_SET_GUEST_DEBUG: {
+ struct kvm_guest_debug dbg;
r = -EFAULT;
if (copy_from_user(&dbg, argp, sizeof dbg))
goto out;
- r = kvm_arch_vcpu_ioctl_debug_guest(vcpu, &dbg);
+ r = kvm_arch_vcpu_ioctl_set_guest_debug(vcpu, &dbg);
if (r)
goto out;
r = 0;