diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1d6f0459cd7bbe531b7acc2d85722ff62185729e..47f7b985f833e478699dcda4168da0ff32dec4fa 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -4078,6 +4078,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
plus one apbt timer for broadcast timer.
x86_intel_mid_timer=apbt_only | lapic_and_apbt
+ xen_512gb_limit [KNL,X86-64,XEN]
+ Restricts the kernel running paravirtualized under Xen
+ to use only up to 512 GB of RAM. The reason to do so is
+ crash analysis tools and Xen tools for doing domain
+ save/restore/migration must be enabled to handle larger
+ domains.
+
xen_emul_unplug= [HW,X86,XEN]
Unplug Xen emulated devices
Format: [unplug0,][unplug1]
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index c44a5d53e464733509de6d3d6347cf9b89889c06..10ef14b2616da3512eba872cd580ebcf56e73cdc 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -35,10 +35,6 @@ typedef struct xpaddr {
#define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT)
#define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT)
-/* Maximum amount of memory we can handle in a domain in pages */
-#define MAX_DOMAIN_PAGES \
- ((unsigned long)((u64)CONFIG_XEN_MAX_DOMAIN_MEMORY * 1024 * 1024 * 1024 / PAGE_SIZE))
-
extern unsigned long *machine_to_phys_mapping;
extern unsigned long machine_to_phys_nr;
extern unsigned long *xen_p2m_addr;
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig
index e88fda867a33b198bc356aded57d59f48fcfb4ee..7bcf21b865d11421044f6d2ec2bd23c6c5ffb77b 100644
--- a/arch/x86/xen/Kconfig
+++ b/arch/x86/xen/Kconfig
@@ -23,14 +23,18 @@ config XEN_PVHVM
def_bool y
depends on XEN && PCI && X86_LOCAL_APIC
-config XEN_MAX_DOMAIN_MEMORY
- int
- default 500 if X86_64
- default 64 if X86_32
- depends on XEN
- help
- This only affects the sizing of some bss arrays, the unused
- portions of which are freed.
+config XEN_512GB
+ bool "Limit Xen pv-domain memory to 512GB"
+ depends on XEN && X86_64
+ default y
+ help
+ Limit paravirtualized user domains to 512GB of RAM.
+
+ The Xen tools and crash dump analysis tools might not support
+ pv-domains with more than 512 GB of RAM. This option controls the
+ default setting of the kernel to use only up to 512 GB or more.
+ It is always possible to change the default via specifying the
+ boot parameter "xen_512gb_limit".
config XEN_SAVE_RESTORE
bool
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index c719f7c36cb8c7824c53e1ab9151f284ea91bc5d..c059ca1c82937844df2a94c5ca0b65c9df0473ec 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -517,7 +517,7 @@ static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
*/
static bool alloc_p2m(unsigned long pfn)
{
- unsigned topidx, mididx;
+ unsigned topidx;
unsigned long *top_mfn_p, *mid_mfn;
pte_t *ptep, *pte_pg;
unsigned int level;
@@ -525,9 +525,6 @@ static bool alloc_p2m(unsigned long pfn)
unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
unsigned long p2m_pfn;
- topidx = p2m_top_index(pfn);
- mididx = p2m_mid_index(pfn);
-
ptep = lookup_address(addr, &level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
@@ -539,7 +536,8 @@ static bool alloc_p2m(unsigned long pfn)
return false;
}
- if (p2m_top_mfn) {
+ if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
+ topidx = p2m_top_index(pfn);
top_mfn_p = &p2m_top_mfn[topidx];
mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
@@ -596,7 +594,7 @@ static bool alloc_p2m(unsigned long pfn)
wmb(); /* Tools are synchronizing via p2m_generation. */
HYPERVISOR_shared_info->arch.p2m_generation++;
if (mid_mfn)
- mid_mfn[mididx] = virt_to_mfn(p2m);
+ mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
p2m = NULL;
}
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index b096d02d34ac5319877f1714a2caa9a3b5fa5103..f96002107691a5417d8c3bad4a51572e85e59720 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -33,6 +33,8 @@
#include "p2m.h"
#include "mmu.h"
+#define GB(x) ((uint64_t)(x) * 1024 * 1024 * 1024)
+
/* Amount of extra memory space we add to the e820 ranges */
struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
@@ -69,6 +71,26 @@ static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY;
*/
#define EXTRA_MEM_RATIO (10)
+static bool xen_512gb_limit __initdata = IS_ENABLED(CONFIG_XEN_512GB);
+
+static void __init xen_parse_512gb(void)
+{
+ bool val = false;
+ char *arg;
+
+ arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit");
+ if (!arg)
+ return;
+
+ arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit=");
+ if (!arg)
+ val = true;
+ else if (strtobool(arg + strlen("xen_512gb_limit="), &val))
+ return;
+
+ xen_512gb_limit = val;
+}
+
static void __init xen_add_extra_mem(phys_addr_t start, phys_addr_t size)
{
int i;
@@ -503,12 +525,29 @@ void __init xen_remap_memory(void)
pr_info("Remapped %ld page(s)\n", remapped);
}
+static unsigned long __init xen_get_pages_limit(void)
+{
+ unsigned long limit;
+
+#ifdef CONFIG_X86_32
+ limit = GB(64) / PAGE_SIZE;
+#else
+ limit = ~0ul;
+ if (!xen_initial_domain() && xen_512gb_limit)
+ limit = GB(512) / PAGE_SIZE;
+#endif
+ return limit;
+}
+
static unsigned long __init xen_get_max_pages(void)
{
- unsigned long max_pages = MAX_DOMAIN_PAGES;
+ unsigned long max_pages, limit;
domid_t domid = DOMID_SELF;
int ret;
+ limit = xen_get_pages_limit();
+ max_pages = limit;
+
/*
* For the initial domain we use the maximum reservation as
* the maximum page.
@@ -524,7 +563,7 @@ static unsigned long __init xen_get_max_pages(void)
max_pages = ret;
}
- return min(max_pages, MAX_DOMAIN_PAGES);
+ return min(max_pages, limit);
}
static void __init xen_align_and_add_e820_region(phys_addr_t start,
@@ -699,7 +738,7 @@ static void __init xen_reserve_xen_mfnlist(void)
**/
char * __init xen_memory_setup(void)
{
- unsigned long max_pfn = xen_start_info->nr_pages;
+ unsigned long max_pfn;
phys_addr_t mem_end, addr, size, chunk_size;
u32 type;
int rc;
@@ -709,7 +748,9 @@ char * __init xen_memory_setup(void)
int i;
int op;
- max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
+ xen_parse_512gb();
+ max_pfn = xen_get_pages_limit();
+ max_pfn = min(max_pfn, xen_start_info->nr_pages);
mem_end = PFN_PHYS(max_pfn);
memmap.nr_entries = E820MAX;
@@ -762,12 +803,15 @@ char * __init xen_memory_setup(void)
* is limited to the max size of lowmem, so that it doesn't
* get completely filled.
*
+ * Make sure we have no memory above max_pages, as this area
+ * isn't handled by the p2m management.
+ *
* In principle there could be a problem in lowmem systems if
* the initial memory is also very large with respect to
* lowmem, but we won't try to deal with that here.
*/
- extra_pages = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
- extra_pages);
+ extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
+ extra_pages, max_pages - max_pfn);
i = 0;
addr = xen_e820_map[0].addr;
size = xen_e820_map[0].size;
@@ -803,9 +847,6 @@ char * __init xen_memory_setup(void)
/*
* Set the rest as identity mapped, in case PCI BARs are
* located here.
- *
- * PFNs above MAX_P2M_PFN are considered identity mapped as
- * well.
*/
set_phys_range_identity(addr / PAGE_SIZE, ~0ul);