Mauricio Faria de Oliveira <mauri...@linux.vnet.ibm.com> writes:
> Hi Michael, Michal,
>
> I got back from vacation. Checking this one.
Yeah it got stuck in a rut.
> On 02/20/2018 02:06 PM, Michal Suchánek wrote:
>>> I did it the way I did because otherwise we waste memory on every
>>> system on earth just to support a use case that we don't actually
>>> intend for anyone to ever use - ie. migrating from a patched machine
>>> to an unpatched machine.
>
> If this thread eventually closes in 'ok, so that memory has to be
> reserved/wasted anyway', that can be done only in pseries, right?
>
> It seems not so much memory for this particular platform/hardware.
Yes and no. We certainly have pseries machines with 10s of TBs of
memory, but pseries is also used when running on KVM/Openstack where
some people are interested in running small VMs - so as usual it's not
so simple :)
But it's not *that* much memory so we should probably stop worrying
about it and just always allocate the fallback on pseries.
I *think* the patch below is all we need, as well as some tweaking of
patch 2, are you able to test and repost?
cheers
diff --git a/arch/powerpc/platforms/pseries/setup.c
b/arch/powerpc/platforms/pseries/setup.c
index 1a527625acf7..9116824bd7c5 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -468,26 +468,18 @@ static void pseries_setup_rfi_flush(void)
/* Enable by default */
enable = true;
+ types = L1D_FLUSH_FALLBACK;
rc = plpar_get_cpu_characteristics(&result);
if (rc == H_SUCCESS) {
- types = L1D_FLUSH_NONE;
-
if (result.character & H_CPU_CHAR_L1D_FLUSH_TRIG2)
types |= L1D_FLUSH_MTTRIG;
if (result.character & H_CPU_CHAR_L1D_FLUSH_ORI30)
types |= L1D_FLUSH_ORI;
- /* Use fallback if nothing set in hcall */
- if (types == L1D_FLUSH_NONE)
- types = L1D_FLUSH_FALLBACK;
-
if ((!(result.behaviour & H_CPU_BEHAV_L1D_FLUSH_PR)) ||
(!(result.behaviour & H_CPU_BEHAV_FAVOUR_SECURITY)))
enable = false;
- } else {
- /* Default to fallback if case hcall is not available */
- types = L1D_FLUSH_FALLBACK;
}
setup_rfi_flush(types, enable);
