* [PATCH] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled
@ 2023-03-07 0:34 Haren Myneni
2023-03-08 2:55 ` Nathan Lynch
0 siblings, 1 reply; 3+ messages in thread
From: Haren Myneni @ 2023-03-07 0:34 UTC (permalink / raw)
To: mpe, npiggin, nathanl, linuxppc-dev
The hypervisor supports user-mode NX from Power10. pseries_vas_dlpar_cpu()
is called from lparcfg_write() to update VAS windows for DLPAR CPU event
and the kernel gets -ENOTSUPP for HCALLs if the user-mode NX is not
supported.
This patch ignores updating VAS capabilities and returns success if the
copy/paste feature is not enabled.
Fixes: 2147783d6bf0 ("powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
---
arch/powerpc/platforms/pseries/vas.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 559112312810..dc003849d2c5 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -856,6 +856,13 @@ int pseries_vas_dlpar_cpu(void)
{
int new_nr_creds, rc;
+ /*
+ * NX-GZIP is not enabled. Nothing to do for DLPAR event
+ */
+ if (!copypaste_feat)
+ return 0;
+
+
rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
(u64)virt_to_phys(&hv_cop_caps));
@@ -1012,6 +1019,7 @@ static int __init pseries_vas_init(void)
* Linux supports user space COPY/PASTE only with Radix
*/
if (!radix_enabled()) {
+ copypaste_feat = 0;
pr_err("API is supported only with radix page tables\n");
return -ENOTSUPP;
}
--
2.26.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled
2023-03-07 0:34 [PATCH] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled Haren Myneni
@ 2023-03-08 2:55 ` Nathan Lynch
2023-03-20 7:40 ` Haren Myneni
0 siblings, 1 reply; 3+ messages in thread
From: Nathan Lynch @ 2023-03-08 2:55 UTC (permalink / raw)
To: Haren Myneni; +Cc: linuxppc-dev, npiggin
Haren Myneni <haren@linux.ibm.com> writes:
> The hypervisor supports user-mode NX from Power10. pseries_vas_dlpar_cpu()
> is called from lparcfg_write() to update VAS windows for DLPAR CPU event
> and the kernel gets -ENOTSUPP for HCALLs if the user-mode NX is not
> supported.
The commit text would be improved by more explanation about the higher
level failure mode here. Does lparcfg_write() fail when it shouldn't? If
so, does that cause a processor DLPAR operation to spuriously fail?
pseries_vas_dlpar_cpu() is also called from pseries_vas_notifier() in
dedicated processor mode. Does this problem affect that scenario also?
> This patch ignores updating VAS capabilities and returns success if the
> copy/paste feature is not enabled.
>
> Fixes: 2147783d6bf0 ("powerpc/pseries: Use lparcfg to reconfig VAS windows for DLPAR CPU")
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> ---
> arch/powerpc/platforms/pseries/vas.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
> index 559112312810..dc003849d2c5 100644
> --- a/arch/powerpc/platforms/pseries/vas.c
> +++ b/arch/powerpc/platforms/pseries/vas.c
> @@ -856,6 +856,13 @@ int pseries_vas_dlpar_cpu(void)
> {
> int new_nr_creds, rc;
>
> + /*
> + * NX-GZIP is not enabled. Nothing to do for DLPAR event
> + */
> + if (!copypaste_feat)
> + return 0;
> +
> +
> rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
> vascaps[VAS_GZIP_DEF_FEAT_TYPE].feat,
> (u64)virt_to_phys(&hv_cop_caps));
> @@ -1012,6 +1019,7 @@ static int __init pseries_vas_init(void)
> * Linux supports user space COPY/PASTE only with Radix
> */
> if (!radix_enabled()) {
> + copypaste_feat = 0;
copypaste_feat is a bool, so use false, not 0. But otherwise I think
this looks correct and consistent with the rest of the code in vas.c.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled
2023-03-08 2:55 ` Nathan Lynch
@ 2023-03-20 7:40 ` Haren Myneni
0 siblings, 0 replies; 3+ messages in thread
From: Haren Myneni @ 2023-03-20 7:40 UTC (permalink / raw)
To: Nathan Lynch; +Cc: linuxppc-dev, npiggin
On Tue, 2023-03-07 at 20:55 -0600, Nathan Lynch wrote:
> Haren Myneni <haren@linux.ibm.com> writes:
> > The hypervisor supports user-mode NX from Power10.
> > pseries_vas_dlpar_cpu()
> > is called from lparcfg_write() to update VAS windows for DLPAR CPU
> > event
> > and the kernel gets -ENOTSUPP for HCALLs if the user-mode NX is not
> > supported.
>
> The commit text would be improved by more explanation about the
> higher
> level failure mode here. Does lparcfg_write() fail when it shouldn't?
> If
> so, does that cause a processor DLPAR operation to spuriously fail?
Thanks for your suggestions, I will add more explanation in the
description.
Even if copy/paste is not enabled, pseries_vas_dlpar_cpu() just returns
0 which allows lparcfg_write() returns success - will not affect DLPAR
operation.
if (pseries_vas_dlpar_cpu() != 0)
retval = H_HARDWARE;
>
> pseries_vas_dlpar_cpu() is also called from pseries_vas_notifier() in
> dedicated processor mode. Does this problem affect that scenario
> also?
It should not affect for dedicated processor
mode. pseries_vas_notifier() is registered if copy/paste is enabled.
if (!rc && copypaste_feat) {
if (firmware_has_feature(FW_FEATURE_LPAR))
of_reconfig_notifier_register(&pseries_vas_nb);
>
> > This patch ignores updating VAS capabilities and returns success if
> > the
> > copy/paste feature is not enabled.
> >
> > Fixes: 2147783d6bf0 ("powerpc/pseries: Use lparcfg to reconfig VAS
> > windows for DLPAR CPU")
> > Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> > ---
> > arch/powerpc/platforms/pseries/vas.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/arch/powerpc/platforms/pseries/vas.c
> > b/arch/powerpc/platforms/pseries/vas.c
> > index 559112312810..dc003849d2c5 100644
> > --- a/arch/powerpc/platforms/pseries/vas.c
> > +++ b/arch/powerpc/platforms/pseries/vas.c
> > @@ -856,6 +856,13 @@ int pseries_vas_dlpar_cpu(void)
> > {
> > int new_nr_creds, rc;
> >
> > + /*
> > + * NX-GZIP is not enabled. Nothing to do for DLPAR event
> > + */
> > + if (!copypaste_feat)
> > + return 0;
> > +
> > +
> > rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES,
> > vascaps[VAS_GZIP_DEF_FEAT_TYPE].f
> > eat,
> > (u64)virt_to_phys(&hv_cop_caps));
> > @@ -1012,6 +1019,7 @@ static int __init pseries_vas_init(void)
> > * Linux supports user space COPY/PASTE only with Radix
> > */
> > if (!radix_enabled()) {
> > + copypaste_feat = 0;
>
> copypaste_feat is a bool, so use false, not 0. But otherwise I think
> this looks correct and consistent with the rest of the code in vas.c.
Correct my mistake.
Thanks
Haren
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-03-20 7:41 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2023-03-07 0:34 [PATCH] powerpc/pseries/vas: Ignore VAS update for DLPAR if copy/paste is not enabled Haren Myneni
2023-03-08 2:55 ` Nathan Lynch
2023-03-20 7:40 ` Haren Myneni
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