Re: [Xen-devel] [PATCH v2] x86/hvm: Add MSR old value

[Wei Liu]

On Fri, Oct 13, 2017 at 03:50:57PM +0300, Alexandru Isaila wrote:
> This patch adds the old value param and the onchangeonly option
> to the VM_EVENT_REASON_MOV_TO_MSR event.
> 
> The param was added to the vm_event_mov_to_msr struct and to the
> hvm_monitor_msr function. Finally I've changed the bool_t param
> to a bool for the hvm_msr_write_intercept function.
> 
> Signed-off-by: Alexandru Isaila 
> Acked-by: Tamas K Lengyel 
> 
> ---
> Changes since V1:
>   - Removed Stray blanks inside the inner parentheses
>   - Added space after the if statement
>   - Added * 8 to the set/clear/test_bit statements
>   - Removed the blank line after monitored_msr.
> ---
>  tools/libxc/include/xenctrl.h |  2 +-
>  tools/libxc/xc_monitor.c  |  3 ++-

Acked-by: Wei Liu 

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Re: [Xen-devel] [PATCH v2] x86/hvm: Add MSR old value

[Razvan Cojocaru]

On 10/13/2017 07:26 PM, Tamas K Lengyel wrote:
> On Fri, Oct 13, 2017 at 9:50 AM, Jan Beulich  wrote:
> On 13.10.17 at 14:50,  wrote:
>>> This patch adds the old value param and the onchangeonly option
>>> to the VM_EVENT_REASON_MOV_TO_MSR event.
>>>
>>> The param was added to the vm_event_mov_to_msr struct and to the
>>> hvm_monitor_msr function. Finally I've changed the bool_t param
>>> to a bool for the hvm_msr_write_intercept function.
>>>
>>> Signed-off-by: Alexandru Isaila 
>>> Acked-by: Tamas K Lengyel 
>>
>> I think this should have been dropped with a bug having been fixed
>> (for only cosmetic changes it would be fine to keep). For the bits
>> where it's applicable
>> Acked-by: Jan Beulich 
> 
> Indeed. It's fine for now, my ack still stands.

That was my mistake - I thought that the fix was so obvious that Tamas
couldn't possibly object, and advised Alexandru to keep the ack. We'll
be more careful next time.


Thanks,
Razvan

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Re: [Xen-devel] [PATCH v2] x86/hvm: Add MSR old value

[Tamas K Lengyel]

On Fri, Oct 13, 2017 at 9:50 AM, Jan Beulich  wrote:
 On 13.10.17 at 14:50,  wrote:
>> This patch adds the old value param and the onchangeonly option
>> to the VM_EVENT_REASON_MOV_TO_MSR event.
>>
>> The param was added to the vm_event_mov_to_msr struct and to the
>> hvm_monitor_msr function. Finally I've changed the bool_t param
>> to a bool for the hvm_msr_write_intercept function.
>>
>> Signed-off-by: Alexandru Isaila 
>> Acked-by: Tamas K Lengyel 
>
> I think this should have been dropped with a bug having been fixed
> (for only cosmetic changes it would be fine to keep). For the bits
> where it's applicable
> Acked-by: Jan Beulich 

Indeed. It's fine for now, my ack still stands.

Thanks,
Tamas

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Re: [Xen-devel] [PATCH v2] x86/hvm: Add MSR old value

[Jan Beulich]

>>> On 13.10.17 at 14:50,  wrote:
> This patch adds the old value param and the onchangeonly option
> to the VM_EVENT_REASON_MOV_TO_MSR event.
> 
> The param was added to the vm_event_mov_to_msr struct and to the
> hvm_monitor_msr function. Finally I've changed the bool_t param
> to a bool for the hvm_msr_write_intercept function.
> 
> Signed-off-by: Alexandru Isaila 
> Acked-by: Tamas K Lengyel 

I think this should have been dropped with a bug having been fixed
(for only cosmetic changes it would be fine to keep). For the bits
where it's applicable
Acked-by: Jan Beulich 

Jan


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[Xen-devel] [PATCH v2] x86/hvm: Add MSR old value

[Alexandru Isaila]

This patch adds the old value param and the onchangeonly option
to the VM_EVENT_REASON_MOV_TO_MSR event.

The param was added to the vm_event_mov_to_msr struct and to the
hvm_monitor_msr function. Finally I've changed the bool_t param
to a bool for the hvm_msr_write_intercept function.

Signed-off-by: Alexandru Isaila 
Acked-by: Tamas K Lengyel 

---
Changes since V1:
- Removed Stray blanks inside the inner parentheses
- Added space after the if statement
- Added * 8 to the set/clear/test_bit statements
- Removed the blank line after monitored_msr.
---
 tools/libxc/include/xenctrl.h |  2 +-
 tools/libxc/xc_monitor.c  |  3 ++-
 xen/arch/x86/hvm/hvm.c| 10 --
 xen/arch/x86/hvm/monitor.c|  9 ++---
 xen/arch/x86/monitor.c| 26 +++---
 xen/include/asm-x86/hvm/monitor.h |  2 +-
 xen/include/asm-x86/hvm/support.h |  2 +-
 xen/include/asm-x86/monitor.h |  1 +
 xen/include/public/domctl.h   |  2 ++
 xen/include/public/vm_event.h |  5 +++--
 10 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 3bcab3c..b99d6eb 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2048,7 +2048,7 @@ int xc_monitor_write_ctrlreg(xc_interface *xch, domid_t 
domain_id,
  * non-architectural indices.
  */
 int xc_monitor_mov_to_msr(xc_interface *xch, domid_t domain_id, uint32_t msr,
-  bool enable);
+  bool enable, bool onchangeonly);
 int xc_monitor_singlestep(xc_interface *xch, domid_t domain_id, bool enable);
 int xc_monitor_software_breakpoint(xc_interface *xch, domid_t domain_id,
bool enable);
diff --git a/tools/libxc/xc_monitor.c b/tools/libxc/xc_monitor.c
index 6046680..09d04be 100644
--- a/tools/libxc/xc_monitor.c
+++ b/tools/libxc/xc_monitor.c
@@ -90,7 +90,7 @@ int xc_monitor_write_ctrlreg(xc_interface *xch, domid_t 
domain_id,
 }
 
 int xc_monitor_mov_to_msr(xc_interface *xch, domid_t domain_id, uint32_t msr,
-  bool enable)
+  bool enable, bool onchangeonly)
 {
 DECLARE_DOMCTL;
 
@@ -100,6 +100,7 @@ int xc_monitor_mov_to_msr(xc_interface *xch, domid_t 
domain_id, uint32_t msr,
 : XEN_DOMCTL_MONITOR_OP_DISABLE;
 domctl.u.monitor_op.event = XEN_DOMCTL_MONITOR_EVENT_MOV_TO_MSR;
 domctl.u.monitor_op.u.mov_to_msr.msr = msr;
+domctl.u.monitor_op.u.mov_to_msr.onchangeonly = onchangeonly;
 
 return do_domctl(xch, );
 }
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 205b4cb..0238787 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3489,7 +3489,7 @@ int hvm_msr_read_intercept(unsigned int msr, uint64_t 
*msr_content)
 }
 
 int hvm_msr_write_intercept(unsigned int msr, uint64_t msr_content,
-bool_t may_defer)
+bool may_defer)
 {
 struct vcpu *v = current;
 struct domain *d = v->domain;
@@ -3500,6 +3500,12 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t 
msr_content,
 
 if ( may_defer && unlikely(monitored_msr(v->domain, msr)) )
 {
+uint64_t msr_old_content;
+
+ret = hvm_msr_read_intercept(msr, _old_content);
+if ( ret != X86EMUL_OKAY )
+return ret;
+
 ASSERT(v->arch.vm_event);
 
 /* The actual write will occur in hvm_do_resume() (if permitted). */
@@ -3507,7 +3513,7 @@ int hvm_msr_write_intercept(unsigned int msr, uint64_t 
msr_content,
 v->arch.vm_event->write_data.msr = msr;
 v->arch.vm_event->write_data.value = msr_content;
 
-hvm_monitor_msr(msr, msr_content);
+hvm_monitor_msr(msr, msr_content, msr_old_content);
 return X86EMUL_OKAY;
 }
 
diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
index 4ce778c..131b852 100644
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -74,16 +74,19 @@ bool hvm_monitor_emul_unimplemented(void)
 monitor_traps(curr, true, ) == 1;
 }
 
-void hvm_monitor_msr(unsigned int msr, uint64_t value)
+void hvm_monitor_msr(unsigned int msr, uint64_t new_value, uint64_t old_value)
 {
 struct vcpu *curr = current;
 
-if ( monitored_msr(curr->domain, msr) )
+if ( monitored_msr(curr->domain, msr) &&
+ (!monitored_msr_onchangeonly(curr->domain, msr) ||
+   new_value != old_value) )
 {
 vm_event_request_t req = {
 .reason = VM_EVENT_REASON_MOV_TO_MSR,
 .u.mov_to_msr.msr = msr,
-.u.mov_to_msr.value = value,
+.u.mov_to_msr.new_value = new_value,
+.u.mov_to_msr.old_value = old_value
 };
 
 monitor_traps(curr, 1, );
diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index e59f1f5..ecfa9e5