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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4] x86/monitor: Notify monitor if an emulation fails.
If case of a vm_event with the emulate_flags set, if the instruction
cannot be emulated, the monitor should be notified instead of directly
injecting a hw exception.
This behavior can be used to re-execute an instruction not supported by
the emulator using the real processor (e.g. altp2m) instead of just
crashing.
Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>
---
Changed since v1:
* Removed the emulation kind check when calling hvm_inject_hw_exception
Changed since v2:
* Removed a file added by mistake
Changed since v3:
* Removed extra stray line
* Added the _enabled suffix to the emul_unhandleable monitor option
Changed since v4
* Fixed return expression of hvm_monitor_emul_unhandleable handle
monitor_traps failures.
* Removed stray parantheses.
---
tools/libxc/include/xenctrl.h | 2 ++
tools/libxc/xc_monitor.c | 14 ++++++++++++++
xen/arch/x86/hvm/emulate.c | 7 ++++++-
xen/arch/x86/hvm/monitor.c | 17 +++++++++++++++++
xen/arch/x86/monitor.c | 12 ++++++++++++
xen/include/asm-x86/domain.h | 1 +
xen/include/asm-x86/hvm/monitor.h | 1 +
xen/include/asm-x86/monitor.h | 3 ++-
xen/include/public/domctl.h | 1 +
xen/include/public/vm_event.h | 2 ++
10 files changed, 58 insertions(+), 2 deletions(-)
diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index c51bb3b..8deb5ac 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2029,6 +2029,8 @@ int xc_monitor_debug_exceptions(xc_interface *xch,
domid_t domain_id,
int xc_monitor_cpuid(xc_interface *xch, domid_t domain_id, bool enable);
int xc_monitor_privileged_call(xc_interface *xch, domid_t domain_id,
bool enable);
+int xc_monitor_emul_unhandleable(xc_interface *xch, domid_t domain_id,
+ bool enable);
/**
* 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 b44ce93..8e72c6c 100644
--- a/tools/libxc/xc_monitor.c
+++ b/tools/libxc/xc_monitor.c
@@ -216,6 +216,20 @@ int xc_monitor_privileged_call(xc_interface *xch, domid_t
domain_id,
return do_domctl(xch, &domctl);
}
+int xc_monitor_emul_unhandleable(xc_interface *xch, domid_t domain_id,
+ bool enable)
+{
+ 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_EMUL_UNHANDLEABLE;
+
+ return do_domctl(xch, &domctl);
+}
+
/*
* Local variables:
* mode: C
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index b2068ad..e1177f8 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -14,12 +14,14 @@
#include <xen/sched.h>
#include <xen/paging.h>
#include <xen/trace.h>
+#include <xen/vm_event.h>
#include <asm/event.h>
#include <asm/i387.h>
#include <asm/xstate.h>
#include <asm/hvm/emulate.h>
#include <asm/hvm/hvm.h>
#include <asm/hvm/ioreq.h>
+#include <asm/hvm/monitor.h>
#include <asm/hvm/trace.h>
#include <asm/hvm/support.h>
#include <asm/hvm/svm/svm.h>
@@ -2104,7 +2106,10 @@ void hvm_emulate_one_vm_event(enum emul_kind kind,
unsigned int trapnr,
return;
case X86EMUL_UNHANDLEABLE:
hvm_dump_emulation_state(XENLOG_G_DEBUG, "Mem event", &ctx);
- hvm_inject_hw_exception(trapnr, errcode);
+ if ( hvm_monitor_emul_unhandleable() )
+ return;
+ else
+ hvm_inject_hw_exception(trapnr, errcode);
break;
case X86EMUL_EXCEPTION:
hvm_inject_event(&ctx.ctxt.event);
diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
index a7ccfc4..e77b05e 100644
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -57,6 +57,23 @@ bool_t hvm_monitor_cr(unsigned int index, unsigned long
value, unsigned long old
return 0;
}
+bool hvm_monitor_emul_unhandleable(void)
+{
+ struct vcpu *curr = current;
+
+ /*
+ * Send a vm_event to the monitor to signal that the current
+ * instruction couldn't be emulated.
+ */
+ vm_event_request_t req = {
+ .reason = VM_EVENT_REASON_EMUL_UNHANDLEABLE,
+ .vcpu_id = curr->vcpu_id,
+ };
+
+ return curr->domain->arch.monitor.emul_unhandleable_enabled &&
+ monitor_traps(curr, true, &req) == 1;
+}
+
void hvm_monitor_msr(unsigned int msr, uint64_t value)
{
struct vcpu *curr = current;
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 706454f..f791372 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -283,6 +283,18 @@ int arch_monitor_domctl_event(struct domain *d,
break;
}
+ case XEN_DOMCTL_MONITOR_EVENT_EMUL_UNHANDLEABLE:
+ {
+ bool old_status = ad->monitor.emul_unhandleable_enabled;
+ if ( unlikely(old_status == requested_status) )
+ return -EEXIST;
+
+ domain_pause(d);
+ ad->monitor.emul_unhandleable_enabled = requested_status;
+ 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 c10522b..ae2d04d 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -405,6 +405,7 @@ struct arch_domain
unsigned int debug_exception_sync : 1;
unsigned int cpuid_enabled : 1;
unsigned int descriptor_access_enabled : 1;
+ unsigned int emul_unhandleable_enabled : 1;
struct monitor_msr_bitmap *msr_bitmap;
uint64_t write_ctrlreg_mask[4];
} monitor;
diff --git a/xen/include/asm-x86/hvm/monitor.h
b/xen/include/asm-x86/hvm/monitor.h
index d9efb35..4030be7 100644
--- a/xen/include/asm-x86/hvm/monitor.h
+++ b/xen/include/asm-x86/hvm/monitor.h
@@ -47,6 +47,7 @@ int hvm_monitor_cpuid(unsigned long insn_length, unsigned int
leaf,
unsigned int subleaf);
void hvm_monitor_interrupt(unsigned int vector, unsigned int type,
unsigned int err, uint64_t cr2);
+bool hvm_monitor_emul_unhandleable(void);
#endif /* __ASM_X86_HVM_MONITOR_H__ */
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index c5c323b..38ba0ff 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)
(1U << XEN_DOMCTL_MONITOR_EVENT_GUEST_REQUEST) |
(1U << XEN_DOMCTL_MONITOR_EVENT_DEBUG_EXCEPTION) |
(1U << XEN_DOMCTL_MONITOR_EVENT_CPUID) |
- (1U << XEN_DOMCTL_MONITOR_EVENT_INTERRUPT);
+ (1U << XEN_DOMCTL_MONITOR_EVENT_INTERRUPT) |
+ (1U << XEN_DOMCTL_MONITOR_EVENT_EMUL_UNHANDLEABLE);
/* 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 ff39762..6bd8666 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -1083,6 +1083,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_psr_cmt_op_t);
#define XEN_DOMCTL_MONITOR_EVENT_PRIVILEGED_CALL 7
#define XEN_DOMCTL_MONITOR_EVENT_INTERRUPT 8
#define XEN_DOMCTL_MONITOR_EVENT_DESC_ACCESS 9
+#define XEN_DOMCTL_MONITOR_EVENT_EMUL_UNHANDLEABLE 10
struct xen_domctl_monitor_op {
uint32_t op; /* XEN_DOMCTL_MONITOR_OP_* */
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index f01e471..5548afb 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -148,6 +148,8 @@
#define VM_EVENT_REASON_INTERRUPT 12
/* A descriptor table register was accessed. */
#define VM_EVENT_REASON_DESCRIPTOR_ACCESS 13
+/* Current instruction couldn't be emulated */
+#define VM_EVENT_REASON_EMUL_UNHANDLEABLE 14
/* Supported values for the vm_event_write_ctrlreg index. */
#define VM_EVENT_X86_CR0 0
--
2.7.4
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