diff mbox series

[v2,2/4] powerpc/pseries: check DRCONF_MEM_RESERVED in lmb_is_removable()

Message ID 20210512202809.95363-3-danielhb413@gmail.com
State Accepted
Headers show
Series Unisolate LMBs DRC on removal error + cleanups | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (1fab3666d738e4af3a7450c44441310e4d7a7e53)
snowpatch_ozlabs/checkpatch warning total: 0 errors, 0 warnings, 1 checks, 9 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Daniel Henrique Barboza May 12, 2021, 8:28 p.m. UTC
DRCONF_MEM_RESERVED is a flag that represents the "Reserved Memory"
status in LOPAR v2.10, section 4.2.8. If a LMB is marked as reserved,
quoting LOPAR, "is not to be used or altered by the base OS". This flag
is read only in the kernel, being set by the firmware/hypervisor in the
DT. As an example, QEMU will set this flag in hw/ppc/spapr.c,
spapr_dt_dynamic_memory().

lmb_is_removable() does not check for DRCONF_MEM_RESERVED. This function
is used in dlpar_remove_lmb() as a guard before the removal logic. Since
it is failing to check for !RESERVED, dlpar_remove_lmb() will fail in a
later stage instead of failing in the validation when receiving a
reserved LMB as input.

lmb_is_removable() is also used in dlpar_memory_remove_by_count() to
evaluate if we have enough LMBs to complete the request. The missing
!RESERVED check in this case is causing dlpar_memory_remove_by_count()
to miscalculate the number of elegible LMBs for the removal, and can
make it error out later on instead of failing in the validation with the
'not enough LMBs to satisfy request' message.

Making a DRCONF_MEM_RESERVED check in lmb_is_removable() fixes all these
issues.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 arch/powerpc/platforms/pseries/hotplug-memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

David Gibson May 13, 2021, 5:12 a.m. UTC | #1
On Wed, May 12, 2021 at 05:28:07PM -0300, Daniel Henrique Barboza wrote:
> DRCONF_MEM_RESERVED is a flag that represents the "Reserved Memory"
> status in LOPAR v2.10, section 4.2.8. If a LMB is marked as reserved,
> quoting LOPAR, "is not to be used or altered by the base OS". This flag
> is read only in the kernel, being set by the firmware/hypervisor in the
> DT. As an example, QEMU will set this flag in hw/ppc/spapr.c,
> spapr_dt_dynamic_memory().
> 
> lmb_is_removable() does not check for DRCONF_MEM_RESERVED. This function
> is used in dlpar_remove_lmb() as a guard before the removal logic. Since
> it is failing to check for !RESERVED, dlpar_remove_lmb() will fail in a
> later stage instead of failing in the validation when receiving a
> reserved LMB as input.
> 
> lmb_is_removable() is also used in dlpar_memory_remove_by_count() to
> evaluate if we have enough LMBs to complete the request. The missing
> !RESERVED check in this case is causing dlpar_memory_remove_by_count()
> to miscalculate the number of elegible LMBs for the removal, and can
> make it error out later on instead of failing in the validation with the
> 'not enough LMBs to satisfy request' message.
> 
> Making a DRCONF_MEM_RESERVED check in lmb_is_removable() fixes all these
> issues.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  arch/powerpc/platforms/pseries/hotplug-memory.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
> index bb98574a84a2..c21d9278c1ce 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> @@ -348,7 +348,8 @@ static int pseries_remove_mem_node(struct device_node *np)
>  
>  static bool lmb_is_removable(struct drmem_lmb *lmb)
>  {
> -	if (!(lmb->flags & DRCONF_MEM_ASSIGNED))
> +	if ((lmb->flags & DRCONF_MEM_RESERVED) ||
> +		!(lmb->flags & DRCONF_MEM_ASSIGNED))
>  		return false;
>  
>  #ifdef CONFIG_FA_DUMP
diff mbox series

Patch

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index bb98574a84a2..c21d9278c1ce 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -348,7 +348,8 @@  static int pseries_remove_mem_node(struct device_node *np)
 
 static bool lmb_is_removable(struct drmem_lmb *lmb)
 {
-	if (!(lmb->flags & DRCONF_MEM_ASSIGNED))
+	if ((lmb->flags & DRCONF_MEM_RESERVED) ||
+		!(lmb->flags & DRCONF_MEM_ASSIGNED))
 		return false;
 
 #ifdef CONFIG_FA_DUMP