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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v7 2/3] x86/vm_event: Add HVM debug exception vm_events
Since in-guest debug exceptions are now unconditionally trapped to Xen, adding
a hook for vm_event subscribers to tap into this new always-on guest event. We
rename along the way hvm_event_breakpoint_type to hvm_event_type to better
match the various events that can be passed with it. We also introduce the
necessary monitor_op domctl's to enable subscribing to the events.
This patch also provides monitor subscribers to int3 events proper access
to the instruction length necessary for accurate event-reinjection. Without
this subscribers manually have to evaluate if the int3 instruction has any
prefix attached which would change the instruction length.
Signed-off-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
v7: Add rc < 0 clause for crash case in vmx and cosmetic fixes
---
tools/libxc/include/xenctrl.h | 3 +-
tools/libxc/xc_monitor.c | 25 +++++++++++++++
tools/tests/xen-access/xen-access.c | 61 ++++++++++++++++++++++++++++++++-----
xen/arch/x86/hvm/monitor.c | 21 +++++++++++--
xen/arch/x86/hvm/vmx/vmx.c | 46 ++++++++++++++++++++++------
xen/arch/x86/monitor.c | 16 ++++++++++
xen/include/asm-x86/domain.h | 2 ++
xen/include/asm-x86/hvm/monitor.h | 7 +++--
xen/include/asm-x86/monitor.h | 3 +-
xen/include/public/domctl.h | 6 ++++
xen/include/public/vm_event.h | 14 +++++++--
11 files changed, 177 insertions(+), 27 deletions(-)
diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 4f5d954..4a85b4a 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2165,7 +2165,8 @@ int xc_monitor_software_breakpoint(xc_interface *xch,
domid_t domain_id,
bool enable);
int xc_monitor_guest_request(xc_interface *xch, domid_t domain_id,
bool enable, bool sync);
-
+int xc_monitor_debug_exceptions(xc_interface *xch, domid_t domain_id,
+ bool enable, bool sync);
/**
* This function enables / disables emulation for each REP for a
* REP-compatible instruction.
diff --git a/tools/libxc/xc_monitor.c b/tools/libxc/xc_monitor.c
index 78131b2..264992c 100644
--- a/tools/libxc/xc_monitor.c
+++ b/tools/libxc/xc_monitor.c
@@ -156,3 +156,28 @@ int xc_monitor_emulate_each_rep(xc_interface *xch, domid_t
domain_id,
return do_domctl(xch, &domctl);
}
+
+int xc_monitor_debug_exceptions(xc_interface *xch, domid_t domain_id,
+ bool enable, bool sync)
+{
+ DECLARE_DOMCTL;
+
+ domctl.cmd = XEN_DOMCTL_monitor_op;
+ domctl.domain = domain_id;
+ domctl.u.monitor_op.op = enable ? XEN_DOMCTL_MONITOR_OP_ENABLE
+ : XEN_DOMCTL_MONITOR_OP_DISABLE;
+ domctl.u.monitor_op.event = XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION;
+ domctl.u.monitor_op.u.debug_exception.sync = sync;
+
+ return do_domctl(xch, &domctl);
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/tools/tests/xen-access/xen-access.c
b/tools/tests/xen-access/xen-access.c
index f26e723..02655d5 100644
--- a/tools/tests/xen-access/xen-access.c
+++ b/tools/tests/xen-access/xen-access.c
@@ -53,6 +53,10 @@
#define ERROR(a, b...) fprintf(stderr, a "\n", ## b)
#define PERROR(a, b...) fprintf(stderr, a ": %s\n", ## b, strerror(errno))
+/* From xen/include/asm-x86/processor.h */
+#define X86_TRAP_DEBUG 1
+#define X86_TRAP_INT3 3
+
typedef struct vm_event {
domid_t domain_id;
xenevtchn_handle *xce_handle;
@@ -333,7 +337,7 @@ void usage(char* progname)
{
fprintf(stderr, "Usage: %s [-m] <domain_id> write|exec", progname);
#if defined(__i386__) || defined(__x86_64__)
- fprintf(stderr, "|breakpoint|altp2m_write|altp2m_exec");
+ fprintf(stderr, "|breakpoint|altp2m_write|altp2m_exec|debug");
#endif
fprintf(stderr,
"\n"
@@ -354,10 +358,12 @@ int main(int argc, char *argv[])
xc_interface *xch;
xenmem_access_t default_access = XENMEM_access_rwx;
xenmem_access_t after_first_access = XENMEM_access_rwx;
+ int memaccess = 0;
int required = 0;
int breakpoint = 0;
int shutting_down = 0;
int altp2m = 0;
+ int debug = 0;
uint16_t altp2m_view_id = 0;
char* progname = argv[0];
@@ -391,11 +397,13 @@ int main(int argc, char *argv[])
{
default_access = XENMEM_access_rx;
after_first_access = XENMEM_access_rwx;
+ memaccess = 1;
}
else if ( !strcmp(argv[0], "exec") )
{
default_access = XENMEM_access_rw;
after_first_access = XENMEM_access_rwx;
+ memaccess = 1;
}
#if defined(__i386__) || defined(__x86_64__)
else if ( !strcmp(argv[0], "breakpoint") )
@@ -406,11 +414,17 @@ int main(int argc, char *argv[])
{
default_access = XENMEM_access_rx;
altp2m = 1;
+ memaccess = 1;
}
else if ( !strcmp(argv[0], "altp2m_exec") )
{
default_access = XENMEM_access_rw;
altp2m = 1;
+ memaccess = 1;
+ }
+ else if ( !strcmp(argv[0], "debug") )
+ {
+ debug = 1;
}
#endif
else
@@ -446,7 +460,7 @@ int main(int argc, char *argv[])
}
/* With altp2m we just create a new, restricted view of the memory */
- if ( altp2m )
+ if ( memaccess && altp2m )
{
xen_pfn_t gfn = 0;
unsigned long perm_set = 0;
@@ -493,7 +507,7 @@ int main(int argc, char *argv[])
}
}
- if ( !altp2m )
+ if ( memaccess && !altp2m )
{
/* Set the default access type and convert all pages to it */
rc = xc_set_mem_access(xch, domain_id, default_access, ~0ull, 0);
@@ -524,6 +538,16 @@ int main(int argc, char *argv[])
}
}
+ if ( debug )
+ {
+ rc = xc_monitor_debug_exceptions(xch, domain_id, 1, 1);
+ if ( rc < 0 )
+ {
+ ERROR("Error %d setting debug exception listener with vm_event\n",
rc);
+ goto exit;
+ }
+ }
+
/* Wait for access */
for (;;)
{
@@ -534,6 +558,8 @@ int main(int argc, char *argv[])
if ( breakpoint )
rc = xc_monitor_software_breakpoint(xch, domain_id, 0);
+ if ( debug )
+ rc = xc_monitor_debug_exceptions(xch, domain_id, 0, 0);
if ( altp2m )
{
@@ -641,16 +667,16 @@ int main(int argc, char *argv[])
req.vcpu_id);
/* Reinject */
- rc = xc_hvm_inject_trap(
- xch, domain_id, req.vcpu_id, 3,
- HVMOP_TRAP_sw_exc, -1, 0, 0);
+ rc = xc_hvm_inject_trap(xch, domain_id, req.vcpu_id,
+ X86_TRAP_INT3,
+ req.u.software_breakpoint.type, -1,
+ req.u.software_breakpoint.insn_length,
0);
if (rc < 0)
{
ERROR("Error %d injecting breakpoint\n", rc);
interrupted = -1;
continue;
}
-
break;
case VM_EVENT_REASON_SINGLESTEP:
printf("Singlestep: rip=%016"PRIx64", vcpu %d, altp2m %u\n",
@@ -669,6 +695,27 @@ int main(int argc, char *argv[])
rsp.flags |= VM_EVENT_FLAG_TOGGLE_SINGLESTEP;
break;
+ case VM_EVENT_REASON_DEBUG_EXCEPTION:
+ printf("Debug exception: rip=%016"PRIx64", vcpu %d. Type: %u.
Length: %u\n",
+ req.data.regs.x86.rip,
+ req.vcpu_id,
+ req.u.debug_exception.type,
+ req.u.debug_exception.insn_length);
+
+ /* Reinject */
+ rc = xc_hvm_inject_trap(xch, domain_id, req.vcpu_id,
+ X86_TRAP_DEBUG,
+ req.u.debug_exception.type, -1,
+ req.u.debug_exception.insn_length,
+ req.data.regs.x86.cr2);
+ if (rc < 0)
+ {
+ ERROR("Error %d injecting breakpoint\n", rc);
+ interrupted = -1;
+ continue;
+ }
+
+ break;
default:
fprintf(stderr, "UNKNOWN REASON CODE %d\n", req.reason);
}
diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
index 472926c..bbe5952 100644
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -87,12 +87,13 @@ static inline unsigned long gfn_of_rip(unsigned long rip)
return paging_gva_to_gfn(curr, sreg.base + rip, &pfec);
}
-int hvm_monitor_breakpoint(unsigned long rip,
- enum hvm_monitor_breakpoint_type type)
+int hvm_monitor_debug(unsigned long rip, enum hvm_monitor_debug_type type,
+ unsigned long trap_type, unsigned long insn_length)
{
struct vcpu *curr = current;
struct arch_domain *ad = &curr->domain->arch;
vm_event_request_t req = {};
+ bool_t sync;
switch ( type )
{
@@ -101,6 +102,9 @@ int hvm_monitor_breakpoint(unsigned long rip,
return 0;
req.reason = VM_EVENT_REASON_SOFTWARE_BREAKPOINT;
req.u.software_breakpoint.gfn = gfn_of_rip(rip);
+ req.u.software_breakpoint.type = trap_type;
+ req.u.software_breakpoint.insn_length = insn_length;
+ sync = 1;
break;
case HVM_MONITOR_SINGLESTEP_BREAKPOINT:
@@ -108,6 +112,17 @@ int hvm_monitor_breakpoint(unsigned long rip,
return 0;
req.reason = VM_EVENT_REASON_SINGLESTEP;
req.u.singlestep.gfn = gfn_of_rip(rip);
+ sync = 1;
+ break;
+
+ case HVM_MONITOR_DEBUG_EXCEPTION:
+ if ( !ad->monitor.debug_exception_enabled )
+ return 0;
+ req.reason = VM_EVENT_REASON_DEBUG_EXCEPTION;
+ req.u.debug_exception.gfn = gfn_of_rip(rip);
+ req.u.debug_exception.type = trap_type;
+ req.u.debug_exception.insn_length = insn_length;
+ sync = !!ad->monitor.debug_exception_sync;
break;
default:
@@ -116,7 +131,7 @@ int hvm_monitor_breakpoint(unsigned long rip,
req.vcpu_id = curr->vcpu_id;
- return vm_event_monitor_traps(curr, 1, &req);
+ return vm_event_monitor_traps(curr, sync, &req);
}
/*
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 9d4121e..5b22d87 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3376,7 +3376,29 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
HVMTRACE_1D(TRAP_DEBUG, exit_qualification);
write_debugreg(6, exit_qualification | DR_STATUS_RESERVED_ONE);
if ( !v->domain->debugger_attached )
- vmx_propagate_intr(intr_info);
+ {
+ unsigned long insn_len = 0;
+ int rc;
+ unsigned long trap_type = MASK_EXTR(intr_info,
+ INTR_INFO_INTR_TYPE_MASK);
+
+ if ( trap_type >= X86_EVENTTYPE_SW_INTERRUPT )
+ __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_len);
+
+ rc = hvm_monitor_debug(regs->eip,
+ HVM_MONITOR_DEBUG_EXCEPTION,
+ trap_type, insn_len);
+
+ /*
+ * !rc continue normally
+ * rc > 0 paused waiting for response, work here is done
+ * rc < 0 error in monitor/vm_event, crash
+ */
+ if ( !rc )
+ vmx_propagate_intr(intr_info);
+ if ( rc < 0 )
+ goto exit_and_crash;
+ }
else
domain_pause_for_debugger();
break;
@@ -3391,9 +3413,14 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
break;
}
else {
- int rc =
- hvm_monitor_breakpoint(regs->eip,
- HVM_MONITOR_SOFTWARE_BREAKPOINT);
+ unsigned long insn_len;
+ int rc;
+
+ __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_len);
+ rc = hvm_monitor_debug(regs->eip,
+ HVM_MONITOR_SOFTWARE_BREAKPOINT,
+ X86_EVENTTYPE_SW_EXCEPTION,
+ insn_len);
if ( !rc )
{
@@ -3401,11 +3428,8 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
.vector = TRAP_int3,
.type = X86_EVENTTYPE_SW_EXCEPTION,
.error_code = HVM_DELIVER_NO_ERROR_CODE,
+ .insn_len = insn_len
};
- unsigned long insn_len;
-
- __vmread(VM_EXIT_INSTRUCTION_LEN, &insn_len);
- trap.insn_len = insn_len;
hvm_inject_trap(&trap);
break;
}
@@ -3720,8 +3744,10 @@ void vmx_vmexit_handler(struct cpu_user_regs *regs)
vmx_update_cpu_exec_control(v);
if ( v->arch.hvm_vcpu.single_step )
{
- hvm_monitor_breakpoint(regs->eip,
- HVM_MONITOR_SINGLESTEP_BREAKPOINT);
+ hvm_monitor_debug(regs->eip,
+ HVM_MONITOR_SINGLESTEP_BREAKPOINT,
+ 0, 0);
+
if ( v->domain->debugger_attached )
domain_pause_for_debugger();
}
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index a271161..205df41 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -224,6 +224,22 @@ int arch_monitor_domctl_event(struct domain *d,
break;
}
+ case XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION:
+ {
+ bool_t old_status = ad->monitor.debug_exception_enabled;
+
+ if ( unlikely(old_status == requested_status) )
+ return -EEXIST;
+
+ domain_pause(d);
+ ad->monitor.debug_exception_enabled = requested_status;
+ ad->monitor.debug_exception_sync = requested_status ?
+ mop->u.debug_exception.sync :
+ 0;
+ domain_unpause(d);
+ break;
+ }
+
default:
/*
* Should not be reached unless arch_monitor_get_capabilities() is
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 7c27f9e..8f64ae9 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -403,6 +403,8 @@ struct arch_domain
unsigned int write_ctrlreg_onchangeonly : 4;
unsigned int singlestep_enabled : 1;
unsigned int software_breakpoint_enabled : 1;
+ unsigned int debug_exception_enabled : 1;
+ unsigned int debug_exception_sync : 1;
struct monitor_msr_bitmap *msr_bitmap;
} monitor;
diff --git a/xen/include/asm-x86/hvm/monitor.h
b/xen/include/asm-x86/hvm/monitor.h
index 55d435e..8b0f119 100644
--- a/xen/include/asm-x86/hvm/monitor.h
+++ b/xen/include/asm-x86/hvm/monitor.h
@@ -23,10 +23,11 @@
#include <xen/paging.h>
#include <public/vm_event.h>
-enum hvm_monitor_breakpoint_type
+enum hvm_monitor_debug_type
{
HVM_MONITOR_SOFTWARE_BREAKPOINT,
HVM_MONITOR_SINGLESTEP_BREAKPOINT,
+ HVM_MONITOR_DEBUG_EXCEPTION,
};
/*
@@ -39,8 +40,8 @@ bool_t hvm_monitor_cr(unsigned int index, unsigned long value,
#define hvm_monitor_crX(cr, new, old) \
hvm_monitor_cr(VM_EVENT_X86_##cr, new, old)
void hvm_monitor_msr(unsigned int msr, uint64_t value);
-int hvm_monitor_breakpoint(unsigned long rip,
- enum hvm_monitor_breakpoint_type type);
+int hvm_monitor_debug(unsigned long rip, enum hvm_monitor_debug_type type,
+ unsigned long trap_type, unsigned long insn_length);
#endif /* __ASM_X86_HVM_MONITOR_H__ */
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index 94b6768..a9db3c0 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -77,7 +77,8 @@ static inline uint32_t arch_monitor_get_capabilities(struct
domain *d)
capabilities = (1U << XEN_DOMCTL_MONITOR_EVENT_WRITE_CTRLREG) |
(1U << XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR) |
(1U << XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT) |
- (1U << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST);
+ (1U << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST) |
+ (1U << XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION);
/* Since we know this is on VMX, we can just call the hvm func */
if ( hvm_is_singlestep_supported() )
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 7be3924..30020ba 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -1080,6 +1080,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_psr_cmt_op_t);
#define XEN_DOMCTL_MONITOR_EVENT_SINGLESTEP 2
#define XEN_DOMCTL_MONITOR_EVENT_SOFTWARE_BREAKPOINT 3
#define XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST 4
+#define XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION 5
struct xen_domctl_monitor_op {
uint32_t op; /* XEN_DOMCTL_MONITOR_OP_* */
@@ -1114,6 +1115,11 @@ struct xen_domctl_monitor_op {
/* Pause vCPU until response */
uint8_t sync;
} guest_request;
+
+ struct {
+ /* Pause vCPU until response */
+ uint8_t sync;
+ } debug_exception;
} u;
};
typedef struct xen_domctl_monitor_op xen_domctl_monitor_op_t;
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index 9270d52..68bddfb 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -29,7 +29,7 @@
#include "xen.h"
-#define VM_EVENT_INTERFACE_VERSION 0x00000001
+#define VM_EVENT_INTERFACE_VERSION 0x00000002
#if defined(__XEN__) || defined(__XEN_TOOLS__)
@@ -119,6 +119,8 @@
#define VM_EVENT_REASON_SINGLESTEP 7
/* An event has been requested via HVMOP_guest_request_vm_event. */
#define VM_EVENT_REASON_GUEST_REQUEST 8
+/* A debug exception was caught */
+#define VM_EVENT_REASON_DEBUG_EXCEPTION 9
/* Supported values for the vm_event_write_ctrlreg index. */
#define VM_EVENT_X86_CR0 0
@@ -203,8 +205,15 @@ struct vm_event_write_ctrlreg {
uint64_t old_value;
};
+struct vm_event_singlestep {
+ uint64_t gfn;
+};
+
struct vm_event_debug {
uint64_t gfn;
+ uint32_t insn_length;
+ uint8_t type; /* HVMOP_TRAP_* */
+ uint8_t _pad[3];
};
struct vm_event_mov_to_msr {
@@ -247,8 +256,9 @@ typedef struct vm_event_st {
struct vm_event_mem_access mem_access;
struct vm_event_write_ctrlreg write_ctrlreg;
struct vm_event_mov_to_msr mov_to_msr;
+ struct vm_event_singlestep singlestep;
struct vm_event_debug software_breakpoint;
- struct vm_event_debug singlestep;
+ struct vm_event_debug debug_exception;
} u;
union {
--
2.8.1
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