On Thu, Sep 23, 2021 at 11:40 AM Lorenzo Pieralisi
[off-list ref] wrote:

On Thu, Sep 23, 2021 at 01:09:58AM +0200, Mark Kettenis wrote:

quoted

quoted

Date: Wed, 22 Sep 2021 17:33:36 +0100
From: Lorenzo Pieralisi <redacted>

On Fri, Sep 10, 2021 at 10:32:23PM +0800, Jia He wrote:

quoted

This reverts commit 437b38c51162f8b87beb28a833c4d5dc85fa864e.

After this commit, a boot panic is alway hit on an Ampere EMAG server
with call trace as follows:
 Internal error: synchronous external abort: 96000410 [#1] SMP
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0+ #462
 Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 0.14 02/22/2019
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[...snip...]
 Call trace:
  acpi_ex_system_memory_space_handler+0x26c/0x2c8
  acpi_ev_address_space_dispatch+0x228/0x2c4
  acpi_ex_access_region+0x114/0x268
  acpi_ex_field_datum_io+0x128/0x1b8
  acpi_ex_extract_from_field+0x14c/0x2ac
  acpi_ex_read_data_from_field+0x190/0x1b8
  acpi_ex_resolve_node_to_value+0x1ec/0x288
  acpi_ex_resolve_to_value+0x250/0x274
  acpi_ds_evaluate_name_path+0xac/0x124
  acpi_ds_exec_end_op+0x90/0x410
  acpi_ps_parse_loop+0x4ac/0x5d8
  acpi_ps_parse_aml+0xe0/0x2c8
  acpi_ps_execute_method+0x19c/0x1ac
  acpi_ns_evaluate+0x1f8/0x26c
  acpi_ns_init_one_device+0x104/0x140
  acpi_ns_walk_namespace+0x158/0x1d0
  acpi_ns_initialize_devices+0x194/0x218
  acpi_initialize_objects+0x48/0x50
  acpi_init+0xe0/0x498

As mentioned by Lorenzo:
  "We are forcing memory semantics mappings to PROT_NORMAL_NC, which
  eMAG does not like at all and I'd need to understand why. It looks
  like the issue happen in SystemMemory Opregion handler."

Hence just revert it before everything is clear.

Fixes: 437b38c51162 ("ACPI: Add memory semantics to acpi_os_map_memory()")
Cc: Lorenzo Pieralisi <redacted>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Rafael J. Wysocki <redacted>
Cc: Harb Abdulhamid <redacted>

Signed-off-by: Jia He <redacted>

Rewrote the commit log, please take the patch below and repost
it as a v3.

It would still be great if Ampere can help us understand why
the NormalNC attributes trigger a sync abort on the opregion
before merging it.

To be honest, I don't think you really need an explanation from Ampere
here.  Mapping a part of the address space that doesn't provide memory
semantics with NormalNC attributes is wrong and triggering a sync
abort in that case is way better than silently ignoring the access.

That's understood and that's what I explained in the revert commit
log, no question about it.

I was just asking to confirm if that's what's actually happening.

quoted

Putting my OpenBSD hat on (where we have our own ACPI OSPM
implementation) I must say that we always interpreted SystemMemory as
memory mapped IO and I think that is a logical choice as SystemIO is
used for (non-memory mapped) IO.  And I'd say that the ACPI OSPM code
should make sure that it uses properly aligned access to any Field
object that doesn't use AnyAcc as its access type.  Even on x86!  And
I'd say that AML that uses AnyAcc fields for SystemMemory OpRegions on
arm64 is buggy.

But maybe relaxing this when the EFI memory map indicates that the
address space in question does provide memory semantics does make
sense.  That should defenitely be documented in the ACPI standard
though.

Mapping SystemMemory Opregions as "memory" does not make sense
at all to me. Still, that's what Linux ACPICA code does (*if*
that's what acpi_os_map_memory() is supposed to mean).

https://lore.kernel.org/linux-acpi/20210916160827.GA4525@lpieralisi (local)

It doesn't need to do that, though, if there are good enough arguments
to change the current behavior (and the argument here is that it may
be an MMIO region, so mapping it as memory doesn't really work, but it
also may be a region in memory - there is no rule in the spec by which
SystemMemory Opregions cannot be "memory" AFAICS) and if that change
doesn't introduce regressions in the installed base.

Where do we go from here, to be defined, we still have a bug
to fix after the revert is applied.

drivers/acpi/sysfs.c

maps BERT error regions with acpi_os_map_memory().

That mechanism is basically used for exporting ACPI tables to user
space and they are known to reside in memory.  Whether or not BERT
regions should be mapped in the same way is a good question.

If the BERT error
region is not in the EFI memory map, we map that memory as device-nGnRnE
and we execute memory semantics operation on it.

https://lore.kernel.org/linux-acpi/e548e72c-83a4-2366-dd57-3e746040fea9@arm.com (local)

I could change that code to map those regions as ioremap_wc() because
supposedly we *know* that's memory but this is becoming a slippery
slope to follow IMO.

quoted

quoted

-- >8 --
Subject: [PATCH] Revert "ACPI: Add memory semantics to acpi_os_map_memory()"

This reverts commit 437b38c51162f8b87beb28a833c4d5dc85fa864e.

The memory semantics added in commit 437b38c51162 causes SystemMemory
Operation region, whose address range is not described in the EFI memory
map to be mapped as NormalNC memory on arm64 platforms (through
acpi_os_map_memory() in acpi_ex_system_memory_space_handler()).

This triggers the following abort on an ARM64 Ampere eMAG machine,
because presumably the physical address range area backing the Opregion
does not support NormalNC memory attributes driven on the bus.

 Internal error: synchronous external abort: 96000410 [#1] SMP
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0+ #462
 Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 0.14 02/22/2019
 pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[...snip...]
 Call trace:
  acpi_ex_system_memory_space_handler+0x26c/0x2c8
  acpi_ev_address_space_dispatch+0x228/0x2c4
  acpi_ex_access_region+0x114/0x268
  acpi_ex_field_datum_io+0x128/0x1b8
  acpi_ex_extract_from_field+0x14c/0x2ac
  acpi_ex_read_data_from_field+0x190/0x1b8
  acpi_ex_resolve_node_to_value+0x1ec/0x288
  acpi_ex_resolve_to_value+0x250/0x274
  acpi_ds_evaluate_name_path+0xac/0x124
  acpi_ds_exec_end_op+0x90/0x410
  acpi_ps_parse_loop+0x4ac/0x5d8
  acpi_ps_parse_aml+0xe0/0x2c8
  acpi_ps_execute_method+0x19c/0x1ac
  acpi_ns_evaluate+0x1f8/0x26c
  acpi_ns_init_one_device+0x104/0x140
  acpi_ns_walk_namespace+0x158/0x1d0
  acpi_ns_initialize_devices+0x194/0x218
  acpi_initialize_objects+0x48/0x50
  acpi_init+0xe0/0x498

If the Opregion address range is not present in the EFI memory map there
is no way for us to determine the memory attributes to use to map it -
defaulting to NormalNC does not work (and it is not correct on a memory
region that may have read side-effects) and therefore commit
437b38c51162 should be reverted, which means reverting back to the
original behavior whereby address ranges that are mapped using
acpi_os_map_memory() default to the safe devicenGnRnE attributes on
ARM64 if the mapped address range is not defined in the EFI memory map.

Fixes: 437b38c51162 ("ACPI: Add memory semantics to acpi_os_map_memory()")
Signed-off-by: Jia He <redacted>
Cc: Lorenzo Pieralisi <redacted>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Rafael J. Wysocki <redacted>
Cc: Harb Abdulhamid <redacted>
---
 arch/arm64/include/asm/acpi.h |  3 ---
 arch/arm64/kernel/acpi.c      | 19 +++----------------
 drivers/acpi/osl.c            | 23 +++++++----------------
 include/acpi/acpi_io.h        |  8 --------
 4 files changed, 10 insertions(+), 43 deletions(-)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 7535dc7cc5aa..bd68e1b7f29f 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h

@@ -50,9 +50,6 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
 void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size);
 #define acpi_os_ioremap acpi_os_ioremap

-void __iomem *acpi_os_memmap(acpi_physical_address phys, acpi_size size);
-#define acpi_os_memmap acpi_os_memmap
-
 typedef u64 phys_cpuid_t;
 #define PHYS_CPUID_INVALID INVALID_HWID

diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 1c9c2f7a1c04..f3851724fe35 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c

@@ -273,8 +273,7 @@ pgprot_t __acpi_get_mem_attribute(phys_addr_t addr)
    return __pgprot(PROT_DEVICE_nGnRnE);
 }

-static void __iomem *__acpi_os_ioremap(acpi_physical_address phys,
-                                  acpi_size size, bool memory)
+void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
 {
    efi_memory_desc_t *md, *region = NULL;
    pgprot_t prot;

@@ -300,11 +299,9 @@ static void __iomem *__acpi_os_ioremap(acpi_physical_address phys,
     * It is fine for AML to remap regions that are not represented in the
     * EFI memory map at all, as it only describes normal memory, and MMIO
     * regions that require a virtual mapping to make them accessible to
-    * the EFI runtime services. Determine the region default
-    * attributes by checking the requested memory semantics.
+    * the EFI runtime services.
     */
-   prot = memory ? __pgprot(PROT_NORMAL_NC) :
-                   __pgprot(PROT_DEVICE_nGnRnE);
+   prot = __pgprot(PROT_DEVICE_nGnRnE);
    if (region) {
            switch (region->type) {
            case EFI_LOADER_CODE:

@@ -364,16 +361,6 @@ static void __iomem *__acpi_os_ioremap(acpi_physical_address phys,
    return __ioremap(phys, size, prot);
 }

-void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size)
-{
-   return __acpi_os_ioremap(phys, size, false);
-}
-
-void __iomem *acpi_os_memmap(acpi_physical_address phys, acpi_size size)
-{
-   return __acpi_os_ioremap(phys, size, true);
-}
-
 /*
  * Claim Synchronous External Aborts as a firmware first notification.
  *

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index a43f1521efe6..45c5c0e45e33 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c

@@ -284,8 +284,7 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
 #define should_use_kmap(pfn)   page_is_ram(pfn)
 #endif

-static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz,
-                         bool memory)
+static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz)
 {
    unsigned long pfn;

@@ -295,8 +294,7 @@ static void __iomem *acpi_map(acpi_physical_address pg_off, unsigned long pg_sz,
                    return NULL;
            return (void __iomem __force *)kmap(pfn_to_page(pfn));
    } else
-           return memory ? acpi_os_memmap(pg_off, pg_sz) :
-                           acpi_os_ioremap(pg_off, pg_sz);
+           return acpi_os_ioremap(pg_off, pg_sz);
 }

 static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)

@@ -311,10 +309,9 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
 }

 /**
- * __acpi_os_map_iomem - Get a virtual address for a given physical address range.
+ * acpi_os_map_iomem - Get a virtual address for a given physical address range.
  * @phys: Start of the physical address range to map.
  * @size: Size of the physical address range to map.
- * @memory: true if remapping memory, false if IO
  *
  * Look up the given physical address range in the list of existing ACPI memory
  * mappings.  If found, get a reference to it and return a pointer to it (its

@@ -324,8 +321,8 @@ static void acpi_unmap(acpi_physical_address pg_off, void __iomem *vaddr)
  * During early init (when acpi_permanent_mmap has not been set yet) this
  * routine simply calls __acpi_map_table() to get the job done.
  */
-static void __iomem __ref
-*__acpi_os_map_iomem(acpi_physical_address phys, acpi_size size, bool memory)
+void __iomem __ref
+*acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
 {
    struct acpi_ioremap *map;
    void __iomem *virt;

@@ -356,7 +353,7 @@ static void __iomem __ref

    pg_off = round_down(phys, PAGE_SIZE);
    pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
-   virt = acpi_map(phys, size, memory);
+   virt = acpi_map(phys, size);
    if (!virt) {
            mutex_unlock(&acpi_ioremap_lock);
            kfree(map);

@@ -375,17 +372,11 @@ static void __iomem __ref
    mutex_unlock(&acpi_ioremap_lock);
    return map->virt + (phys - map->phys);
 }
-
-void __iomem *__ref
-acpi_os_map_iomem(acpi_physical_address phys, acpi_size size)
-{
-   return __acpi_os_map_iomem(phys, size, false);
-}
 EXPORT_SYMBOL_GPL(acpi_os_map_iomem);

 void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
-   return (void *)__acpi_os_map_iomem(phys, size, true);
+   return (void *)acpi_os_map_iomem(phys, size);
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);

diff --git a/include/acpi/acpi_io.h b/include/acpi/acpi_io.h
index a0212e67d6f4..027faa8883aa 100644
--- a/include/acpi/acpi_io.h
+++ b/include/acpi/acpi_io.h

@@ -14,14 +14,6 @@ static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
 }
 #endif

-#ifndef acpi_os_memmap
-static inline void __iomem *acpi_os_memmap(acpi_physical_address phys,
-                                       acpi_size size)
-{
-   return ioremap_cache(phys, size);
-}
-#endif
-
 extern bool acpi_permanent_mmap;

 void __iomem __ref
--

2.31.0

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