[PATCH v2 1/2] xen/x86: make XEN_BALLOON_MEMORY_HOTPLUG_LIMIT depend on MEMORY_HOTPLUG

From: Roger Pau Monne
Date: Wed Mar 24 2021 - 08:26:23 EST


The Xen memory hotplug limit should depend on the memory hotplug
generic option, rather than the Xen balloon configuration. It's
possible to have a kernel with generic memory hotplug enabled, but
without Xen balloon enabled, at which point memory hotplug won't work
correctly due to the size limitation of the p2m.

Rename the option to XEN_MEMORY_HOTPLUG_LIMIT since it's no longer
tied to ballooning.

Fixes: 9e2369c06c8a18 ("xen: add helpers to allocate unpopulated memory")
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
arch/x86/xen/p2m.c | 4 ++--
drivers/xen/Kconfig | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 17d80f751fcb..a33902d05e45 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -98,8 +98,8 @@ EXPORT_SYMBOL_GPL(xen_p2m_size);
unsigned long xen_max_p2m_pfn __read_mostly;
EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);

-#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
-#define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
+#ifdef CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
+#define P2M_LIMIT CONFIG_XEN_MEMORY_HOTPLUG_LIMIT
#else
#define P2M_LIMIT 0
#endif
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 41645fe6ad48..ea0efd290c37 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -50,11 +50,11 @@ config XEN_BALLOON_MEMORY_HOTPLUG

SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"

-config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
+config XEN_MEMORY_HOTPLUG_LIMIT
int "Hotplugged memory limit (in GiB) for a PV guest"
default 512
depends on XEN_HAVE_PVMMU
- depends on XEN_BALLOON_MEMORY_HOTPLUG
+ depends on MEMORY_HOTPLUG
help
Maxmium amount of memory (in GiB) that a PV guest can be
expanded to when using memory hotplug.
--
2.30.1