From 2b514ec72706a31bea0c3b97e622b81535b5323a Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Wed, 24 Mar 2021 13:24:23 +0100 Subject: [PATCH 1/2] xen/x86: make XEN_BALLOON_MEMORY_HOTPLUG_LIMIT depend on MEMORY_HOTPLUG MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20210324122424.58685-2-roger.pau@citrix.com Signed-off-by: Boris Ostrovsky --- 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. From af44a387e743ab7aa39d3fb5e29c0a973cf91bdc Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Wed, 24 Mar 2021 13:24:24 +0100 Subject: [PATCH 2/2] Revert "xen: fix p2m size in dom0 for disabled memory hotplug case" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This partially reverts commit 882213990d32 ("xen: fix p2m size in dom0 for disabled memory hotplug case") There's no need to special case XEN_UNPOPULATED_ALLOC anymore in order to correctly size the p2m. The generic memory hotplug option has already been tied together with the Xen hotplug limit, so enabling memory hotplug should already trigger a properly sized p2m on Xen PV. Note that XEN_UNPOPULATED_ALLOC depends on ZONE_DEVICE which pulls in MEMORY_HOTPLUG. Leave the check added to __set_phys_to_machine and the adjusted comment about EXTRA_MEM_RATIO. Signed-off-by: Roger Pau Monné Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20210324122424.58685-3-roger.pau@citrix.com [boris: fixed formatting issues] Signed-off-by: Boris Ostrovsky --- arch/x86/include/asm/xen/page.h | 12 ------------ arch/x86/xen/p2m.c | 3 --- arch/x86/xen/setup.c | 16 ++++++++++++++-- 3 files changed, 14 insertions(+), 17 deletions(-) diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index 7068e4bb057d..1a162e559753 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -86,18 +86,6 @@ clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, } #endif -/* - * The maximum amount of extra memory compared to the base size. The - * main scaling factor is the size of struct page. At extreme ratios - * of base:extra, all the base memory can be filled with page - * structures for the extra memory, leaving no space for anything - * else. - * - * 10x seems like a reasonable balance between scaling flexibility and - * leaving a practically usable system. - */ -#define XEN_EXTRA_MEM_RATIO (10) - /* * Helper functions to write or read unsigned long values to/from * memory, when the access may fault. diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index a33902d05e45..ac06ca32e9ef 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -416,9 +416,6 @@ void __init xen_vmalloc_p2m_tree(void) xen_p2m_last_pfn = xen_max_p2m_pfn; p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; - if (!p2m_limit && IS_ENABLED(CONFIG_XEN_UNPOPULATED_ALLOC)) - p2m_limit = xen_start_info->nr_pages * XEN_EXTRA_MEM_RATIO; - vm.flags = VM_ALLOC; vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), PMD_SIZE * PMDS_PER_MID_PAGE); diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c index 1a3b75652fa4..8bfc10330107 100644 --- a/arch/x86/xen/setup.c +++ b/arch/x86/xen/setup.c @@ -59,6 +59,18 @@ static struct { } xen_remap_buf __initdata __aligned(PAGE_SIZE); static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY; +/* + * The maximum amount of extra memory compared to the base size. The + * main scaling factor is the size of struct page. At extreme ratios + * of base:extra, all the base memory can be filled with page + * structures for the extra memory, leaving no space for anything + * else. + * + * 10x seems like a reasonable balance between scaling flexibility and + * leaving a practically usable system. + */ +#define EXTRA_MEM_RATIO (10) + static bool xen_512gb_limit __initdata = IS_ENABLED(CONFIG_XEN_512GB); static void __init xen_parse_512gb(void) @@ -778,13 +790,13 @@ char * __init xen_memory_setup(void) extra_pages += max_pages - max_pfn; /* - * Clamp the amount of extra memory to a XEN_EXTRA_MEM_RATIO + * Clamp the amount of extra memory to a EXTRA_MEM_RATIO * factor the base size. * * Make sure we have no memory above max_pages, as this area * isn't handled by the p2m management. */ - extra_pages = min3(XEN_EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), + extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), extra_pages, max_pages - max_pfn); i = 0; addr = xen_e820_table.entries[0].addr;