[PATCH] powerpc/epapr: add "memory" as a clobber to all hypercalls

[PATCH] powerpc/epapr: add "memory" as a clobber to all hypercalls

[Timur Tabi]

The "memory" clobber tells the compiler to ensure that all writes to memory
are committed before the hypercall is made.

"memory" is only necessary for hcalls where the Hypervisor will read or
write guest memory. However, we add it to all hcalls because the impact is
minimal, and we want to ensure that it's present for the hcalls that need it.

Signed-off-by: Timur Tabi <timur@freescale.com>
---
 arch/powerpc/include/asm/epapr_hcalls.h |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/epapr_hcalls.h b/arch/powerpc/include/asm/epapr_hcalls.h
index f3b0c2c..976835d 100644
--- a/arch/powerpc/include/asm/epapr_hcalls.h
+++ b/arch/powerpc/include/asm/epapr_hcalls.h
@@ -134,10 +134,15 @@
  * whether they will be clobbered.
  *
  * Note that r11 can be used as an output parameter.
+ *
+ * The "memory" clobber is only necessary for hcalls where the Hypervisor
+ * will read or write guest memory. However, we add it to all hcalls because
+ * the impact is minimal, and we want to ensure that it's present for the
+ * hcalls that need it.
 */
 
 /* List of common clobbered registers.  Do not use this macro. */
-#define EV_HCALL_CLOBBERS "r0", "r12", "xer", "ctr", "lr", "cc"
+#define EV_HCALL_CLOBBERS "r0", "r12", "xer", "ctr", "lr", "cc", "memory"
 
 #define EV_HCALL_CLOBBERS8 EV_HCALL_CLOBBERS
 #define EV_HCALL_CLOBBERS7 EV_HCALL_CLOBBERS8, "r10"
-- 
1.7.3.4

Re: [PATCH] powerpc/epapr: add "memory" as a clobber to all hypercalls

[Kumar Gala]

On Mar 15, 2012, at 5:41 PM, Timur Tabi wrote:

> The "memory" clobber tells the compiler to ensure that all writes to =
memory
> are committed before the hypercall is made.
>=20
> "memory" is only necessary for hcalls where the Hypervisor will read =
or
> write guest memory. However, we add it to all hcalls because the =
impact is
> minimal, and we want to ensure that it's present for the hcalls that =
need it.
>=20
> Signed-off-by: Timur Tabi <timur@freescale.com>
> ---
> arch/powerpc/include/asm/epapr_hcalls.h |    7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)

applied

- k=