Re: [Xen-devel] [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

2017-03-20 Thread Yu Zhang 



On 3/21/2017 9:18 AM, Yu Zhang wrote:



On 3/21/2017 1:03 AM, Jan Beulich wrote:

On 18.03.17 at 11:53,  wrote:

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, 
unsigned long gla,

   (npfec.write_access &&
(p2m_is_discard_write(p2mt) || (p2mt == 
p2m_ioreq_server))) )

  {
-__put_gfn(p2m, gfn);
-if ( ap2m_active )
-__put_gfn(hostp2m, gfn);
-
  rc = 0;
  if ( unlikely(is_pvh_domain(currd)) )
-goto out;
+goto out_put_gfn;

Did you forget to re-base onto staging before you've sent this?
is_pvh_domain() was gone before your submission already. When
re-basing, feel free to also drop the dead "rc = 0;" line.


Oops...
I did a rebase days ago, but did not send the patch directly. There 
were some XenGT test performed based on these patch.

Sorry, I should have a check.  Will resend the patch. :)



BTW, since there's another change - "drop the rc = 0", I'd like to send 
the new patchset with a new version nubmer. :-)


Yu


___
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel



___
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

Re: [Xen-devel] [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

2017-03-20 Thread Yu Zhang 



On 3/21/2017 1:03 AM, Jan Beulich wrote:

On 18.03.17 at 11:53,  wrote:

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned 
long gla,
   (npfec.write_access &&
(p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
  {
-__put_gfn(p2m, gfn);
-if ( ap2m_active )
-__put_gfn(hostp2m, gfn);
-
  rc = 0;
  if ( unlikely(is_pvh_domain(currd)) )
-goto out;
+goto out_put_gfn;

Did you forget to re-base onto staging before you've sent this?
is_pvh_domain() was gone before your submission already. When
re-basing, feel free to also drop the dead "rc = 0;" line.


Oops...
I did a rebase days ago, but did not send the patch directly. There were 
some XenGT test performed based on these patch.

Sorry, I should have a check.  Will resend the patch. :)

B.R.
Yu

Jan





___
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

Re: [Xen-devel] [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

2017-03-20 Thread Jan Beulich 
>>> On 18.03.17 at 11:53,  wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned 
> long gla,
>   (npfec.write_access &&
>(p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
>  {
> -__put_gfn(p2m, gfn);
> -if ( ap2m_active )
> -__put_gfn(hostp2m, gfn);
> -
>  rc = 0;
>  if ( unlikely(is_pvh_domain(currd)) )
> -goto out;
> +goto out_put_gfn;

Did you forget to re-base onto staging before you've sent this?
is_pvh_domain() was gone before your submission already. When
re-basing, feel free to also drop the dead "rc = 0;" line.

Jan


___
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

[Xen-devel] [PATCH v8 1/5] x86/ioreq server: Release the p2m lock after mmio is handled.

2017-03-18 Thread Yu Zhang 
Routine hvmemul_do_io() may need to peek the p2m type of a gfn to
select the ioreq server. For example, operations on gfns with
p2m_ioreq_server type will be delivered to a corresponding ioreq
server, and this requires that the p2m type not be switched back
to p2m_ram_rw during the emulation process. To avoid this race
condition, we delay the release of p2m lock in hvm_hap_nested_page_fault()
until mmio is handled.

Note: previously in hvm_hap_nested_page_fault(), put_gfn() was moved
before the handling of mmio, due to a deadlock risk between the p2m
lock and the event lock(in commit 77b8dfe). Later, a per-event channel
lock was introduced in commit de6acb7, to send events. So we do not
need to worry about the deadlock issue.

Signed-off-by: Yu Zhang 
Reviewed-by: Jan Beulich 
---
Cc: Paul Durrant 
Cc: Jan Beulich 
Cc: Andrew Cooper 
---
 xen/arch/x86/hvm/hvm.c | 8 ++--
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index ccfae4f..a9db7f7 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1870,18 +1870,14 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned 
long gla,
  (npfec.write_access &&
   (p2m_is_discard_write(p2mt) || (p2mt == p2m_ioreq_server))) )
 {
-__put_gfn(p2m, gfn);
-if ( ap2m_active )
-__put_gfn(hostp2m, gfn);
-
 rc = 0;
 if ( unlikely(is_pvh_domain(currd)) )
-goto out;
+goto out_put_gfn;
 
 if ( !handle_mmio_with_translation(gla, gpa >> PAGE_SHIFT, npfec) )
 hvm_inject_hw_exception(TRAP_gp_fault, 0);
 rc = 1;
-goto out;
+goto out_put_gfn;
 }
 
 /* Check if the page has been paged out */
-- 
1.9.1


___
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel