| Message ID | 1434534230-17249-2-git-send-email-andre.przywara@arm.com |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Wed, Jun 17, 2015 at 10:43:48AM +0100, Andre Przywara wrote: > Instead of referring to the Linux header including the barrier > macros, copy over the rather simple implementation for the PowerPC > barrier instructions kvmtool uses. This fixes build for powerpc. > > Signed-off-by: Andre Przywara <andre.przywara@arm.com> > --- > Hi, > > I just took what kvmtool seems to have used before, I actually have > no idea if "sync" is the right instruction or "lwsync" would do. > Would be nice if some people with PowerPC knowledge could comment. I *think* we can use lwsync for rmb and wmb, but would want confirmation from a ppc guy before making that change! Will -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 17.06.15 12:15, Will Deacon wrote: > On Wed, Jun 17, 2015 at 10:43:48AM +0100, Andre Przywara wrote: >> Instead of referring to the Linux header including the barrier >> macros, copy over the rather simple implementation for the PowerPC >> barrier instructions kvmtool uses. This fixes build for powerpc. >> >> Signed-off-by: Andre Przywara <andre.przywara@arm.com> >> --- >> Hi, >> >> I just took what kvmtool seems to have used before, I actually have >> no idea if "sync" is the right instruction or "lwsync" would do. >> Would be nice if some people with PowerPC knowledge could comment. > > I *think* we can use lwsync for rmb and wmb, but would want confirmation > from a ppc guy before making that change! Also I'd prefer to play safe for now :) Alex -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2015-06-17 at 11:15 +0100, Will Deacon wrote: > On Wed, Jun 17, 2015 at 10:43:48AM +0100, Andre Przywara wrote: > > Instead of referring to the Linux header including the barrier > > macros, copy over the rather simple implementation for the PowerPC > > barrier instructions kvmtool uses. This fixes build for powerpc. > > > > Signed-off-by: Andre Przywara <andre.przywara@arm.com> > > --- > > Hi, > > > > I just took what kvmtool seems to have used before, I actually have > > no idea if "sync" is the right instruction or "lwsync" would do. > > Would be nice if some people with PowerPC knowledge could comment. > > I *think* we can use lwsync for rmb and wmb, but would want confirmation > from a ppc guy before making that change! Ugh, memory barriers :) You probably can use lwsync, assuming you're only ordering cacheable vs cacheable. But, lwsync has given us pain in the past[1], so I'd be happier if you just used sync. cheers [1]: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=51d7d5205d3389a32859f9939f1093f267409929 -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jun 18, 2015 at 10:11:58AM +0100, Michael Ellerman wrote: > On Wed, 2015-06-17 at 11:15 +0100, Will Deacon wrote: > > On Wed, Jun 17, 2015 at 10:43:48AM +0100, Andre Przywara wrote: > > > Instead of referring to the Linux header including the barrier > > > macros, copy over the rather simple implementation for the PowerPC > > > barrier instructions kvmtool uses. This fixes build for powerpc. > > > > > > Signed-off-by: Andre Przywara <andre.przywara@arm.com> > > > --- > > > Hi, > > > > > > I just took what kvmtool seems to have used before, I actually have > > > no idea if "sync" is the right instruction or "lwsync" would do. > > > Would be nice if some people with PowerPC knowledge could comment. > > > > I *think* we can use lwsync for rmb and wmb, but would want confirmation > > from a ppc guy before making that change! > > Ugh, memory barriers :) I prefer to call them "Job Security" :) > You probably can use lwsync, assuming you're only ordering cacheable vs > cacheable. > > But, lwsync has given us pain in the past[1], so I'd be happier if you just used > sync. No probs. I pushed Andre's original patch. Will -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/powerpc/include/kvm/barrier.h b/powerpc/include/kvm/barrier.h index dd5115a..4b708ae 100644 --- a/powerpc/include/kvm/barrier.h +++ b/powerpc/include/kvm/barrier.h @@ -1,6 +1,8 @@ #ifndef _KVM_BARRIER_H_ #define _KVM_BARRIER_H_ -#include <asm/barrier.h> +#define mb() asm volatile ("sync" : : : "memory") +#define rmb() asm volatile ("sync" : : : "memory") +#define wmb() asm volatile ("sync" : : : "memory") #endif /* _KVM_BARRIER_H_ */
Instead of referring to the Linux header including the barrier macros, copy over the rather simple implementation for the PowerPC barrier instructions kvmtool uses. This fixes build for powerpc. Signed-off-by: Andre Przywara <andre.przywara@arm.com> --- Hi, I just took what kvmtool seems to have used before, I actually have no idea if "sync" is the right instruction or "lwsync" would do. Would be nice if some people with PowerPC knowledge could comment. Cheers, Andre. powerpc/include/kvm/barrier.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)