Memory regions that are reserved using efi_mem_reserve_persistent() are recorded in a special EFI config table which survives kexec, allowing the incoming kernel to honour them as well. However, such reservations are not visible in /proc/iomem, and so the kexec tools that load the incoming kernel and its initrd into memory may overwrite these reserved regions before the incoming kernel has a chance to reserve them from further use.
So add these reservations to /proc/iomem as they are created. Note that reservations that are inherited from a previous kernel are memblock_reserve()'d early on, so they are already visible in /proc/iomem. Cc: Masayoshi Mizuma <[email protected]> Cc: [email protected] Cc: [email protected] Signed-off-by: Ard Biesheuvel <[email protected]> --- drivers/firmware/efi/efi.c | 29 ++++++++++++++++++-- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index d101f072c8f8..fcd82dde23c8 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -979,6 +979,24 @@ static int __init efi_memreserve_map_root(void) return 0; } +static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size) +{ + struct resource *res, *parent; + + res = kzalloc(sizeof(struct resource), GFP_ATOMIC); + if (!res) + return -ENOMEM; + + res->name = "reserved"; + res->flags = IORESOURCE_MEM; + res->start = addr; + res->end = addr + size - 1; + + /* we expect a conflict with a 'System RAM' region */ + parent = request_resource_conflict(&iomem_resource, res); + return parent ? request_resource(parent, res) : 0; +} + int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) { struct linux_efi_memreserve *rsv; @@ -1001,9 +1019,8 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) if (index < rsv->size) { rsv->entry[index].base = addr; rsv->entry[index].size = size; - memunmap(rsv); - return 0; + return efi_mem_reserve_iomem(addr, size); } memunmap(rsv); } @@ -1013,6 +1030,12 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) if (!rsv) return -ENOMEM; + rc = efi_mem_reserve_iomem(__pa(rsv), SZ_4K); + if (rc) { + free_page(rsv); + return rc; + } + /* * The memremap() call above assumes that a linux_efi_memreserve entry * never crosses a page boundary, so let's ensure that this remains true @@ -1029,7 +1052,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) efi_memreserve_root->next = __pa(rsv); spin_unlock(&efi_mem_reserve_persistent_lock); - return 0; + return efi_mem_reserve_iomem(addr, size); } static int __init efi_memreserve_root_init(void) -- 2.17.1 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
