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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 5/8] x86/vm-event/monitor: don't compromise monitor_write_data on domain cleanup
The arch_vm_event structure is dynamically allocated and freed @
vm_event_cleanup_domain. This cleanup is triggered e.g. when the toolstack user
disables domain monitoring (xc_monitor_disable), which in turn effectively
discards any information that was in arch_vm_event.write_data.
But this can yield unexpected behavior since if a CR-write was awaiting to be
committed on the scheduling tail (hvm_do_resume->arch_monitor_write_data)
before xc_monitor_disable is called, then the domain CR write is wrongfully
ignored, which of course, in these cases, can easily render a domain crash.
To fix the issue, this patch makes only arch_vm_event.emul_read_data dynamically
allocated instead of the whole arch_vm_event structure. With this we can avoid
invalidation of an awaiting arch_vm_event.write_data by selectively cleaning up
only emul_read_data and emulate_flags @ vm_event_cleanup_domain.
Small note: arch_vm_event structure definition needed to be moved from
asm-x86/vm_event.h to asm-x86/domain.h in the process.
Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
---
xen/arch/x86/domain.c | 5 ++--
xen/arch/x86/hvm/emulate.c | 8 +++---
xen/arch/x86/hvm/hvm.c | 62 ++++++++++++++++++------------------------
xen/arch/x86/mm/p2m.c | 4 +--
xen/arch/x86/monitor.c | 7 +----
xen/arch/x86/vm_event.c | 16 +++++------
xen/include/asm-x86/domain.h | 42 +++++++++++++++++-----------
xen/include/asm-x86/monitor.h | 3 +-
xen/include/asm-x86/vm_event.h | 10 -------
9 files changed, 73 insertions(+), 84 deletions(-)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index bb59247..06e68ae 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -492,8 +492,9 @@ int vcpu_initialise(struct vcpu *v)
void vcpu_destroy(struct vcpu *v)
{
- xfree(v->arch.vm_event);
- v->arch.vm_event = NULL;
+ v->arch.vm_event.emulate_flags = 0;
+ xfree(v->arch.vm_event.emul_read_data);
+ v->arch.vm_event.emul_read_data = NULL;
if ( is_pv_32bit_vcpu(v) )
{
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 855af4d..68f5515 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -73,12 +73,12 @@ static int set_context_data(void *buffer, unsigned int size)
{
struct vcpu *curr = current;
- if ( curr->arch.vm_event )
+ if ( curr->arch.vm_event.emul_read_data )
{
unsigned int safe_size =
- min(size, curr->arch.vm_event->emul_read_data.size);
+ min(size, curr->arch.vm_event.emul_read_data->size);
- memcpy(buffer, curr->arch.vm_event->emul_read_data.data, safe_size);
+ memcpy(buffer, curr->arch.vm_event.emul_read_data->data, safe_size);
memset(buffer + safe_size, 0, size - safe_size);
return X86EMUL_OKAY;
}
@@ -523,7 +523,7 @@ static int hvmemul_virtual_to_linear(
* vm_event being triggered for repeated writes to a whole page.
*/
if ( unlikely(current->domain->arch.mem_access_emulate_each_rep) &&
- current->arch.vm_event->emulate_flags != 0 )
+ current->arch.vm_event.emulate_flags != 0 )
max_reps = 1;
/*
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 884ae40..03dffb8 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -473,24 +473,24 @@ void hvm_do_resume(struct vcpu *v)
if ( !handle_hvm_io_completion(v) )
return;
- if ( unlikely(v->arch.vm_event) )
+ if ( unlikely(v->arch.vm_event.emulate_flags) )
{
- if ( v->arch.vm_event->emulate_flags )
- {
- enum emul_kind kind = EMUL_KIND_NORMAL;
+ enum emul_kind kind;
- if ( v->arch.vm_event->emulate_flags &
- VM_EVENT_FLAG_SET_EMUL_READ_DATA )
- kind = EMUL_KIND_SET_CONTEXT;
- else if ( v->arch.vm_event->emulate_flags &
- VM_EVENT_FLAG_EMULATE_NOWRITE )
- kind = EMUL_KIND_NOWRITE;
+ ASSERT(v->arch.vm_event.emul_read_data);
- hvm_mem_access_emulate_one(kind, TRAP_invalid_op,
- HVM_DELIVER_NO_ERROR_CODE);
+ kind = EMUL_KIND_NORMAL;
- v->arch.vm_event->emulate_flags = 0;
- }
+ if ( v->arch.vm_event.emulate_flags & VM_EVENT_FLAG_SET_EMUL_READ_DATA
)
+ kind = EMUL_KIND_SET_CONTEXT;
+ else if ( v->arch.vm_event.emulate_flags &
+ VM_EVENT_FLAG_EMULATE_NOWRITE )
+ kind = EMUL_KIND_NOWRITE;
+
+ hvm_mem_access_emulate_one(kind, TRAP_invalid_op,
+ HVM_DELIVER_NO_ERROR_CODE);
+
+ v->arch.vm_event.emulate_flags = 0;
}
arch_monitor_write_data(v);
@@ -2178,17 +2178,15 @@ int hvm_set_cr0(unsigned long value, bool_t may_defer)
if ( may_defer && unlikely(v->domain->arch.monitor.write_ctrlreg_enabled &
monitor_ctrlreg_bitmask(VM_EVENT_X86_CR0)) )
{
- ASSERT(v->arch.vm_event);
-
if ( hvm_monitor_crX(CR0, value, old_value) )
{
/*
* The actual write will occur in arch_monitor_write_data(), if
* permitted.
*/
- ASSERT(MWS_NOWRITE == v->arch.vm_event->write_data.status);
- v->arch.vm_event->write_data.status = MWS_CR0;
- v->arch.vm_event->write_data.value = value;
+ ASSERT(MWS_NOWRITE == v->arch.vm_event.write_data.status);
+ v->arch.vm_event.write_data.status = MWS_CR0;
+ v->arch.vm_event.write_data.value = value;
return X86EMUL_OKAY;
}
@@ -2284,17 +2282,15 @@ int hvm_set_cr3(unsigned long value, bool_t may_defer)
if ( may_defer && unlikely(v->domain->arch.monitor.write_ctrlreg_enabled &
monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3)) )
{
- ASSERT(v->arch.vm_event);
-
if ( hvm_monitor_crX(CR3, value, old) )
{
/*
* The actual write will occur in arch_monitor_write_data(), if
* permitted.
*/
- ASSERT(MWS_NOWRITE == v->arch.vm_event->write_data.status);
- v->arch.vm_event->write_data.status = MWS_CR3;
- v->arch.vm_event->write_data.value = value;
+ ASSERT(MWS_NOWRITE == v->arch.vm_event.write_data.status);
+ v->arch.vm_event.write_data.status = MWS_CR3;
+ v->arch.vm_event.write_data.value = value;
return X86EMUL_OKAY;
}
@@ -2368,17 +2364,15 @@ int hvm_set_cr4(unsigned long value, bool_t may_defer)
if ( may_defer && unlikely(v->domain->arch.monitor.write_ctrlreg_enabled &
monitor_ctrlreg_bitmask(VM_EVENT_X86_CR4)) )
{
- ASSERT(v->arch.vm_event);
-
if ( hvm_monitor_crX(CR4, value, old_cr) )
{
/*
* The actual write will occur in arch_monitor_write_data(), if
* permitted.
*/
- ASSERT(MWS_NOWRITE == v->arch.vm_event->write_data.status);
- v->arch.vm_event->write_data.status = MWS_CR4;
- v->arch.vm_event->write_data.value = value;
+ ASSERT(MWS_NOWRITE == v->arch.vm_event.write_data.status);
+ v->arch.vm_event.write_data.status = MWS_CR4;
+ v->arch.vm_event.write_data.value = value;
return X86EMUL_OKAY;
}
@@ -3753,16 +3747,14 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t
msr_content,
if ( may_defer && unlikely(monitored_msr(v->domain, msr)) )
{
- ASSERT(v->arch.vm_event);
-
/*
* The actual write will occur in arch_monitor_write_data(), if
* permitted.
*/
- ASSERT(MWS_NOWRITE == v->arch.vm_event->write_data.status);
- v->arch.vm_event->write_data.status = MWS_MSR;
- v->arch.vm_event->write_data.msr = msr;
- v->arch.vm_event->write_data.value = msr_content;
+ ASSERT(MWS_NOWRITE == v->arch.vm_event.write_data.status);
+ v->arch.vm_event.write_data.status = MWS_MSR;
+ v->arch.vm_event.write_data.msr = msr;
+ v->arch.vm_event.write_data.value = msr_content;
hvm_monitor_msr(msr, msr_content);
return X86EMUL_OKAY;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 16733a4..9bcaa8a 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1639,10 +1639,10 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
}
}
- v->arch.vm_event->emulate_flags = violation ? rsp->flags : 0;
+ v->arch.vm_event.emulate_flags = violation ? rsp->flags : 0;
if ( (rsp->flags & VM_EVENT_FLAG_SET_EMUL_READ_DATA) )
- v->arch.vm_event->emul_read_data = rsp->data.emul_read_data;
+ *v->arch.vm_event.emul_read_data = rsp->data.emul_read_data;
}
}
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 5c8d4da..88d14ae 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -46,12 +46,7 @@ void arch_monitor_cleanup_domain(struct domain *d)
void arch_monitor_write_data(struct vcpu *v)
{
- struct monitor_write_data *w;
-
- if ( likely(!v->arch.vm_event) )
- return;
-
- w = &v->arch.vm_event->write_data;
+ struct monitor_write_data *w = &v->arch.vm_event.write_data;
if ( likely(MWS_NOWRITE == w->status) )
return;
diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index 825da48..f21ff10 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -30,12 +30,13 @@ int vm_event_init_domain(struct domain *d)
for_each_vcpu ( d, v )
{
- if ( v->arch.vm_event )
+ if ( v->arch.vm_event.emul_read_data )
continue;
- v->arch.vm_event = xzalloc(struct arch_vm_event);
+ v->arch.vm_event.emul_read_data =
+ xzalloc(struct vm_event_emul_read_data);
- if ( !v->arch.vm_event )
+ if ( !v->arch.vm_event.emul_read_data )
return -ENOMEM;
}
@@ -52,8 +53,9 @@ void vm_event_cleanup_domain(struct domain *d)
for_each_vcpu ( d, v )
{
- xfree(v->arch.vm_event);
- v->arch.vm_event = NULL;
+ v->arch.vm_event.emulate_flags = 0;
+ xfree(v->arch.vm_event.emul_read_data);
+ v->arch.vm_event.emul_read_data = NULL;
}
d->arch.mem_access_emulate_each_rep = 0;
@@ -73,13 +75,11 @@ void vm_event_register_write_resume(struct vcpu *v,
vm_event_response_t *rsp)
{
if ( rsp->flags & VM_EVENT_FLAG_DENY )
{
- ASSERT(v->arch.vm_event);
-
/* deny flag requires the vCPU to be paused */
if ( !atomic_read(&v->vm_event_pause_count) )
return;
- v->arch.vm_event->write_data.status = MWS_NOWRITE;
+ v->arch.vm_event.write_data.status = MWS_NOWRITE;
}
}
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index a22ee6b..7ea5c8f 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -259,21 +259,6 @@ struct pv_domain
struct cpuidmasks *cpuidmasks;
};
-enum monitor_write_status
-{
- MWS_NOWRITE = 0,
- MWS_MSR,
- MWS_CR0,
- MWS_CR3,
- MWS_CR4,
-};
-
-struct monitor_write_data {
- enum monitor_write_status status;
- uint32_t msr;
- uint64_t value;
-};
-
struct arch_domain
{
struct page_info *perdomain_l3_pg;
@@ -496,6 +481,31 @@ typedef enum __packed {
SMAP_CHECK_DISABLED, /* disable the check */
} smap_check_policy_t;
+enum monitor_write_status
+{
+ MWS_NOWRITE = 0,
+ MWS_MSR,
+ MWS_CR0,
+ MWS_CR3,
+ MWS_CR4,
+};
+
+struct monitor_write_data {
+ enum monitor_write_status status;
+ uint32_t msr;
+ uint64_t value;
+};
+
+/*
+ * Should we emulate the next matching instruction on VCPU resume
+ * after a vm_event?
+ */
+struct arch_vm_event {
+ uint32_t emulate_flags;
+ struct vm_event_emul_read_data *emul_read_data;
+ struct monitor_write_data write_data;
+};
+
struct arch_vcpu
{
/*
@@ -569,7 +579,7 @@ struct arch_vcpu
/* A secondary copy of the vcpu time info. */
XEN_GUEST_HANDLE(vcpu_time_info_t) time_info_guest;
- struct arch_vm_event *vm_event;
+ struct arch_vm_event vm_event;
};
smap_check_policy_t smap_policy_change(struct vcpu *v,
diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
index 1068376..984ac4c 100644
--- a/xen/include/asm-x86/monitor.h
+++ b/xen/include/asm-x86/monitor.h
@@ -48,7 +48,8 @@ int arch_monitor_domctl_op(struct domain *d, struct
xen_domctl_monitor_op *mop)
* Enabling mem_access_emulate_each_rep without a vm_event subscriber
* is meaningless.
*/
- if ( d->max_vcpus && d->vcpu[0] && d->vcpu[0]->arch.vm_event )
+ if ( d->max_vcpus && d->vcpu[0] &&
+ d->vcpu[0]->arch.vm_event.emul_read_data )
d->arch.mem_access_emulate_each_rep = !!mop->event;
else
rc = -EINVAL;
diff --git a/xen/include/asm-x86/vm_event.h b/xen/include/asm-x86/vm_event.h
index 026f42e..c83583d 100644
--- a/xen/include/asm-x86/vm_event.h
+++ b/xen/include/asm-x86/vm_event.h
@@ -22,16 +22,6 @@
#include <xen/sched.h>
#include <xen/vm_event.h>
-/*
- * Should we emulate the next matching instruction on VCPU resume
- * after a vm_event?
- */
-struct arch_vm_event {
- uint32_t emulate_flags;
- struct vm_event_emul_read_data emul_read_data;
- struct monitor_write_data write_data;
-};
-
int vm_event_init_domain(struct domain *d);
void vm_event_cleanup_domain(struct domain *d);
--
2.5.0
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