From: "Jonathan (Zhixiong) Zhang" zjzhang@codeaurora.org
On a platform with APEI (ACPI Platform Error Interface) enabled, firmware updates a memory region with hardware error record using nocache attribute. When OS reads the region, since it maps the region with cache attribute even though EFI memory map defines this region as uncached, OS gets stale data and errorneously reports there is no new HW error.
When ghes driver maps the memory region, it uses the cache attribute according to EFI memory map, if EFI memory map feature is enabled.
Since both arch/x86 and arc/ia64 implemented architecture agnostic EFI memory map attribue lookup function, the code is moved from arch/x86 and arch/ia64 into EFI subsystem.
Jonathan (Zhixiong) Zhang (2): efi: arch, x86: arch, ia64: rearrange EFI memmap related functions acpi, apei: use EFI memmap to map GHES memory
arch/ia64/kernel/efi.c | 11 ----------- arch/x86/platform/efi/efi.c | 18 ------------------ drivers/acpi/apei/ghes.c | 13 +++++++++++++ drivers/firmware/efi/efi.c | 27 +++++++++++++++++++++++++++ include/linux/efi.h | 1 + 5 files changed, 41 insertions(+), 29 deletions(-)
From: "Jonathan (Zhixiong) Zhang" zjzhang@codeaurora.org
Both x86 and ia64 implemented efi_mem_attributs function, which is architecture agnositc. This function is moved to efi subsystem.
efi_remap() function is added. If EFI memmap feature is enabled, and if a memory region has attribute of EFI_MEMORY_UC, map it as uncached.
--- This patch was tested on an arm64 platform. It was built on x86 platform.
Signed-off-by: Jonathan (Zhixiong) Zhang zjzhang@codeaurora.org --- arch/ia64/kernel/efi.c | 11 ----------- arch/x86/platform/efi/efi.c | 18 ------------------ drivers/firmware/efi/efi.c | 27 +++++++++++++++++++++++++++ include/linux/efi.h | 1 + 4 files changed, 28 insertions(+), 29 deletions(-)
diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c index c52d7540dc05..ef20ec784b04 100644 --- a/arch/ia64/kernel/efi.c +++ b/arch/ia64/kernel/efi.c @@ -771,17 +771,6 @@ efi_mem_type (unsigned long phys_addr) }
u64 -efi_mem_attributes (unsigned long phys_addr) -{ - efi_memory_desc_t *md = efi_memory_descriptor(phys_addr); - - if (md) - return md->attribute; - return 0; -} -EXPORT_SYMBOL(efi_mem_attributes); - -u64 efi_mem_attribute (unsigned long phys_addr, unsigned long size) { unsigned long end = phys_addr + size; diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index dbc8627a5cdf..88b3ebaeb72f 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -917,24 +917,6 @@ u32 efi_mem_type(unsigned long phys_addr) return 0; }
-u64 efi_mem_attributes(unsigned long phys_addr) -{ - efi_memory_desc_t *md; - void *p; - - if (!efi_enabled(EFI_MEMMAP)) - return 0; - - for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { - md = p; - if ((md->phys_addr <= phys_addr) && - (phys_addr < (md->phys_addr + - (md->num_pages << EFI_PAGE_SHIFT)))) - return md->attribute; - } - return 0; -} - static int __init arch_parse_efi_cmdline(char *str) { if (parse_option_str(str, "old_map")) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 3061bb8629dc..5b42bb6d1fde 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -517,3 +517,30 @@ char * __init efi_md_typeattr_format(char *buf, size_t size, attr & EFI_MEMORY_UC ? "UC" : ""); return buf; } + +u64 efi_mem_attributes(unsigned long phys_addr) +{ + efi_memory_desc_t *md; + void *p; + + if (!efi_enabled(EFI_MEMMAP)) + return 0; + + for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { + md = p; + if ((md->phys_addr <= phys_addr) && + (phys_addr < (md->phys_addr + + (md->num_pages << EFI_PAGE_SHIFT)))) + return md->attribute; + } + return 0; +} + +void __iomem *efi_remap(phys_addr_t phys_addr, size_t size) +{ + if (efi_enabled(EFI_MEMMAP) && + (efi_mem_attributes(phys_addr) & EFI_MEMORY_UC)) + return ioremap(phys_addr, size); + else + return ioremap_cache(phys_addr, size); +} diff --git a/include/linux/efi.h b/include/linux/efi.h index cf7e431cbc73..3279b5acea11 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -891,6 +891,7 @@ extern struct efi_memory_map memmap;
extern int efi_reboot_quirk_mode; extern bool efi_poweroff_required(void); +extern void __iomem *efi_remap(phys_addr_t phys_addr, size_t size);
/* Iterate through an efi_memory_map */ #define for_each_efi_memory_desc(m, md) \
On Mon, 04 May, at 02:02:14PM, Jonathan (Zhixiong) Zhang wrote:
This should be split into two patches, one to remove the duplicate efi_mem_attributes() and the other to create the new efi_ioremap() function.
Note that on x86 we don't leave the EFI memmap mapped throughout runtime, it gets unmapped in efi_free_boot_services().
Which means that the second patch in this series isn't going to work correctly if an error is reported after the kernel has finished booting.
It looks like arm64 leaves the EFI memmap mapped at runtime, right?
Thank you Matt very much for the code review! Pls. see comments inline.
On 5/27/2015 5:31 AM, Matt Fleming wrote:
Makes sense, will do.
Correct, only x86 unmaps EFI memmap since efi_free_boot_services() is not implemented for other architectures, as shown in include/linux/efi.h .
With x86 arch, efi_unmap_memmap() is called in efi_free_boot_services() to unmap EFI memmap, this function is defined in arch/x86/platform/efi/efi.c. It clears EFI_MEMMAP bit in efi flag. Therefore in this case, efi_enabled(EFI_MEMMAP) returns false for x86 platforms with EFI memory map support, after kernel finished booting; efi_remap() function in turn maps the memory region as cached.
Therefore, I believe the second patch in this series will work correctly for above situation as well. How do you think?
From: "Jonathan (Zhixiong) Zhang" zjzhang@codeaurora.org
With ACPI APEI firmware first handling, generic hardware error record is updated by firmware in GHES memory region. After firmware updated GHES memory region, Linux reads stale data from cache.
GHES memory region should be mapped with cache attributes defined by EFI memory map when applicable. If firmware updates DDR directly, EFI memory map would have GHES memory region defined as uncached; If firmware updates cache, EFI memory map would have GHES memory region defined as cached.
When EFI is configued, map IRQ page using efi_remap() provided by EFI subsystem.
Signed-off-by: Jonathan (Zhixiong) Zhang zjzhang@codeaurora.org --- drivers/acpi/apei/ghes.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index e82d0976a5d0..56875ca76aa7 100644 --- a/drivers/acpi/apei/ghes.c +++ b/drivers/acpi/apei/ghes.c @@ -48,6 +48,7 @@ #include <linux/pci.h> #include <linux/aer.h> #include <linux/nmi.h> +#include <linux/efi.h>
#include <acpi/ghes.h> #include <acpi/apei.h> @@ -159,6 +160,7 @@ static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn) return (void __iomem *)vaddr; }
+#ifndef CONFIG_EFI static void __iomem *ghes_ioremap_pfn_irq(u64 pfn) { unsigned long vaddr; @@ -169,6 +171,7 @@ static void __iomem *ghes_ioremap_pfn_irq(u64 pfn)
return (void __iomem *)vaddr; } +#endif
static void ghes_iounmap_nmi(void __iomem *vaddr_ptr) { @@ -180,6 +183,7 @@ static void ghes_iounmap_nmi(void __iomem *vaddr_ptr) arch_apei_flush_tlb_one(vaddr); }
+#ifndef CONFIG_EFI static void ghes_iounmap_irq(void __iomem *vaddr_ptr) { unsigned long vaddr = (unsigned long __force)vaddr_ptr; @@ -189,6 +193,7 @@ static void ghes_iounmap_irq(void __iomem *vaddr_ptr) unmap_kernel_range_noflush(vaddr, PAGE_SIZE); arch_apei_flush_tlb_one(vaddr); } +#endif
static int ghes_estatus_pool_init(void) { @@ -309,7 +314,11 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, vaddr = ghes_ioremap_pfn_nmi(paddr >> PAGE_SHIFT); } else { spin_lock_irqsave(&ghes_ioremap_lock_irq, flags); +#ifdef CONFIG_EFI + vaddr = efi_remap(paddr & PAGE_MASK, PAGE_SIZE); +#else vaddr = ghes_ioremap_pfn_irq(paddr >> PAGE_SHIFT); +#endif } trunk = PAGE_SIZE - offset; trunk = min(trunk, len); @@ -324,7 +333,11 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len, ghes_iounmap_nmi(vaddr); raw_spin_unlock(&ghes_ioremap_lock_nmi); } else { +#ifdef CONFIG_EFI + iounmap(vaddr); +#else ghes_iounmap_irq(vaddr); +#endif spin_unlock_irqrestore(&ghes_ioremap_lock_irq, flags); } }
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Jonathan (Zhixiong) Zhang -
Matt Fleming -
Zhang, Jonathan Zhixiong