This is a note to let you know that I've just added the patch titled

ACPI / APEI: Replace ioremap_page_range() with fixmap

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: acpi-apei-replace-ioremap_page_range-with-fixmap.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 4f89fa286f6729312e227e7c2d764e8e7b9d340e Mon Sep 17 00:00:00 2001

From: James Morse james.morse@arm.com Date: Mon, 6 Nov 2017 18:44:24 +0000 Subject: ACPI / APEI: Replace ioremap_page_range() with fixmap

From: James Morse james.morse@arm.com

commit 4f89fa286f6729312e227e7c2d764e8e7b9d340e upstream.

Replace ghes_io{re,un}map_pfn_{nmi,irq}()s use of ioremap_page_range() with __set_fixmap() as ioremap_page_range() may sleep to allocate a new level of page-table, even if its passed an existing final-address to use in the mapping.

The GHES driver can only be enabled for architectures that select HAVE_ACPI_APEI: Add fixmap entries to both x86 and arm64.

clear_fixmap() does the TLB invalidation in __set_fixmap() for arm64 and __set_pte_vaddr() for x86. In each case its the same as the respective arch_apei_flush_tlb_one().

Reported-by: Fengguang Wu fengguang.wu@intel.com Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: James Morse james.morse@arm.com Reviewed-by: Borislav Petkov bp@suse.de Tested-by: Tyler Baicar tbaicar@codeaurora.org Tested-by: Toshi Kani toshi.kani@hpe.com [ For the arm64 bits: ] Acked-by: Will Deacon will.deacon@arm.com [ For the x86 bits: ] Acked-by: Ingo Molnar mingo@kernel.org Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc: All applicable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/arm64/include/asm/fixmap.h | 7 ++++++ arch/x86/include/asm/fixmap.h | 6 +++++ drivers/acpi/apei/ghes.c | 44 ++++++++++++---------------------------- 3 files changed, 27 insertions(+), 30 deletions(-)

--- a/arch/arm64/include/asm/fixmap.h +++ b/arch/arm64/include/asm/fixmap.h @@ -51,6 +51,13 @@ enum fixed_addresses {

FIX_EARLYCON_MEM_BASE, FIX_TEXT_POKE0, + +#ifdef CONFIG_ACPI_APEI_GHES + /* Used for GHES mapping from assorted contexts */ + FIX_APEI_GHES_IRQ, + FIX_APEI_GHES_NMI, +#endif /* CONFIG_ACPI_APEI_GHES */ + __end_of_permanent_fixed_addresses,

/* --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -104,6 +104,12 @@ enum fixed_addresses { FIX_GDT_REMAP_BEGIN, FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1,

+#ifdef CONFIG_ACPI_APEI_GHES + /* Used for GHES mapping from assorted contexts */ + FIX_APEI_GHES_IRQ, + FIX_APEI_GHES_NMI, +#endif + __end_of_permanent_fixed_addresses,

/* --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -51,6 +51,7 @@ #include <acpi/actbl1.h> #include <acpi/ghes.h> #include <acpi/apei.h> +#include <asm/fixmap.h> #include <asm/tlbflush.h> #include <ras/ras_event.h>

@@ -112,7 +113,7 @@ static DEFINE_MUTEX(ghes_list_mutex); * Because the memory area used to transfer hardware error information * from BIOS to Linux can be determined only in NMI, IRQ or timer * handler, but general ioremap can not be used in atomic context, so - * a special version of atomic ioremap is implemented for that. + * the fixmap is used instead. */

/* @@ -126,8 +127,8 @@ static DEFINE_MUTEX(ghes_list_mutex); /* virtual memory area for atomic ioremap */ static struct vm_struct *ghes_ioremap_area; /* - * These 2 spinlock is used to prevent atomic ioremap virtual memory - * area from being mapped simultaneously. + * These 2 spinlocks are used to prevent the fixmap entries from being used + * simultaneously. */ static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi); static DEFINE_SPINLOCK(ghes_ioremap_lock_irq); @@ -159,53 +160,36 @@ static void ghes_ioremap_exit(void)

static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn) { - unsigned long vaddr; phys_addr_t paddr; pgprot_t prot;

- vaddr = (unsigned long)GHES_IOREMAP_NMI_PAGE(ghes_ioremap_area->addr); - paddr = pfn << PAGE_SHIFT; prot = arch_apei_get_mem_attribute(paddr); - ioremap_page_range(vaddr, vaddr + PAGE_SIZE, paddr, prot); + __set_fixmap(FIX_APEI_GHES_NMI, paddr, prot);

- return (void __iomem *)vaddr; + return (void __iomem *) fix_to_virt(FIX_APEI_GHES_NMI); }

static void __iomem *ghes_ioremap_pfn_irq(u64 pfn) { - unsigned long vaddr; phys_addr_t paddr; pgprot_t prot;

- vaddr = (unsigned long)GHES_IOREMAP_IRQ_PAGE(ghes_ioremap_area->addr); - paddr = pfn << PAGE_SHIFT; prot = arch_apei_get_mem_attribute(paddr); + __set_fixmap(FIX_APEI_GHES_IRQ, paddr, prot);

- ioremap_page_range(vaddr, vaddr + PAGE_SIZE, paddr, prot); - - return (void __iomem *)vaddr; + return (void __iomem *) fix_to_virt(FIX_APEI_GHES_IRQ); }

-static void ghes_iounmap_nmi(void __iomem *vaddr_ptr) +static void ghes_iounmap_nmi(void) { - unsigned long vaddr = (unsigned long __force)vaddr_ptr; - void *base = ghes_ioremap_area->addr; - - BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_NMI_PAGE(base)); - unmap_kernel_range_noflush(vaddr, PAGE_SIZE); - arch_apei_flush_tlb_one(vaddr); + clear_fixmap(FIX_APEI_GHES_NMI); }

-static void ghes_iounmap_irq(void __iomem *vaddr_ptr) +static void ghes_iounmap_irq(void) { - unsigned long vaddr = (unsigned long __force)vaddr_ptr; - void *base = ghes_ioremap_area->addr; - - BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_IRQ_PAGE(base)); - unmap_kernel_range_noflush(vaddr, PAGE_SIZE); - arch_apei_flush_tlb_one(vaddr); + clear_fixmap(FIX_APEI_GHES_IRQ); }

static int ghes_estatus_pool_init(void) @@ -361,10 +345,10 @@ static void ghes_copy_tofrom_phys(void * paddr += trunk; buffer += trunk; if (in_nmi) { - ghes_iounmap_nmi(vaddr); + ghes_iounmap_nmi(); raw_spin_unlock(&ghes_ioremap_lock_nmi); } else { - ghes_iounmap_irq(vaddr); + ghes_iounmap_irq(); spin_unlock_irqrestore(&ghes_ioremap_lock_irq, flags); } }

Patches currently in stable-queue which might be from james.morse@arm.com are

queue-4.14/acpi-apei-replace-ioremap_page_range-with-fixmap.patch