The NVIDIA Tegra234 VDK is a simulation platform for the Orin SoC. It
supports a subset of the peripherals that will be available in the final
chip and serves as a bootstrapping platform.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Enable support for the BPMP on Tegra234 to avoid relying on Tegra194
being enabled to pull in the needed OF device ID table entry.
On simulation platforms the BPMP hasn't booted up yet by the time we
probe the BPMP driver and the BPMP hasn't had a chance to mark the
doorbell as ringable by the CCPLEX. This corresponding check in the
BPMP driver will therefore fail. Work around this by disabling the
check on simulation platforms.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The PMC block is largely similar to that found on earlier chips, but
not completely compatible. Allow binding to the instantiation found on
Tegra234.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Move the definitions of reset sources and levels into a more natural
location.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The MISC block is largely similar to that found on earlier chips, but
not completely compatible. Allow binding to the instantiation found on
Tegra234.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Add support for FUSE block found on the Tegra234 SoC, which is largely
similar to the IP found on previous generations.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This function can be used by drivers to determine whether code is
running on silicon or on a simulation platform.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This function extracts the PRE_SI_PLATFORM field from the HIDREV
register and can be used to determine which platform the kernel runs on
(silicon, simulation, ...). Note that while only Tegra194 and later
define this field, it should be safe to call this on prior generations
as well since this field should read as 0, indicating silicon.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Summit SMB3xx series is a Programmable Switching Li+ Battery Charger.
This patch adds device-tree binding for Summit SMB345, SMB347 and SMB358
chargers.
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The PMC found on Tegra234 is mostly similar to the one on Tegra194 but
supports slightly different I/O pads and wake events.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The Tegra234 FUSE block is very similar to that on prior chips but not
completely compatible. Document the new compatible string.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The NVIDIA Tegra234 VDK is a simulation platform for the Orin SoC. It
supports a subset of the peripherals that will be available in the final
chip and serves as a bootstrapping platform.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The MISC block found on Tegra234 is mostly similar to the one on
Tegra194 but supports slightly different register sets that make
it incompatible.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Add the missing compatible string for the Tegra194 MISC block.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
The compatible string for the Tegra210 APBMISC block was missing from
the bindings. Add it and while at it, rewrite the description of the
compatible string to make it clearer.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Modernized Loongson64 uses a hierarchical organization for interrupt
controllers (INTCs), all INTC nodes (not only leaf nodes) need some IRQ
numbers. This means 280 (i.e., NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + 256)
is not enough to represent all interrupts, so let's increase NR_IRQS to
320 (NR_IRQS_LEGACY + NR_MIPS_CPU_IRQS + NR_MAX_CHAINED_IRQS + 256).
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
In tx2_uncore_pmu_init_dev(), a call to acpi_dev_get_resources() is used
to create a list _CRS resources which is searched for the device base
address. There is an error check following this:
if (!rentry->res)
return NULL
In no case, will rentry->res be NULL, so the test is useless. Even
if the test worked, it comes before the resource list memory is
freed. None of this really matters as long as the ACPI table has
the memory resource. Let's clean it up so that it makes sense and
will give a meaningful error should firmware leave out the memory
resource.
Fixes: 69c32972d5 ("drivers/perf: Add Cavium ThunderX2 SoC UNCORE PMU driver")
Signed-off-by: Mark Salter <msalter@redhat.com>
Link: https://lore.kernel.org/r/20200915204110.326138-2-msalter@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>
This splat was reported on newer Fedora kernels booting on certain
X-gene based machines:
xgene-pmu APMC0D83:00: X-Gene PMU version 3
Unable to handle kernel read from unreadable memory at virtual \
address 0000000000004006
...
Call trace:
string+0x50/0x100
vsnprintf+0x160/0x750
devm_kvasprintf+0x5c/0xb4
devm_kasprintf+0x54/0x60
__devm_ioremap_resource+0xdc/0x1a0
devm_ioremap_resource+0x14/0x20
acpi_get_pmu_hw_inf.isra.0+0x84/0x15c
acpi_pmu_dev_add+0xbc/0x21c
acpi_ns_walk_namespace+0x16c/0x1e4
acpi_walk_namespace+0xb4/0xfc
xgene_pmu_probe_pmu_dev+0x7c/0xe0
xgene_pmu_probe.part.0+0x2c0/0x310
xgene_pmu_probe+0x54/0x64
platform_drv_probe+0x60/0xb4
really_probe+0xe8/0x4a0
driver_probe_device+0xe4/0x100
device_driver_attach+0xcc/0xd4
__driver_attach+0xb0/0x17c
bus_for_each_dev+0x6c/0xb0
driver_attach+0x30/0x40
bus_add_driver+0x154/0x250
driver_register+0x84/0x140
__platform_driver_register+0x54/0x60
xgene_pmu_driver_init+0x28/0x34
do_one_initcall+0x40/0x204
do_initcalls+0x104/0x144
kernel_init_freeable+0x198/0x210
kernel_init+0x20/0x12c
ret_from_fork+0x10/0x18
Code: 91000400 110004e1 eb08009f 540000c0 (38646846)
---[ end trace f08c10566496a703 ]---
This is due to use of an uninitialized local resource struct in the xgene
pmu driver. The thunderx2_pmu driver avoids this by using the resource list
constructed by acpi_dev_get_resources() rather than using a callback from
that function. The callback in the xgene driver didn't fully initialize
the resource. So get rid of the callback and search the resource list as
done by thunderx2.
Fixes: 832c927d11 ("perf: xgene: Add APM X-Gene SoC Performance Monitoring Unit driver")
Signed-off-by: Mark Salter <msalter@redhat.com>
Link: https://lore.kernel.org/r/20200915204110.326138-1-msalter@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>
Fix the following warnings.
‘set_memory_valid’ [-Wmissing-prototypes]
int set_memory_valid(unsigned long addr, int numpages, int enable)
^
‘set_direct_map_invalid_noflush’ [-Wmissing-prototypes]
int set_direct_map_invalid_noflush(struct page *page)
^
‘set_direct_map_default_noflush’ [-Wmissing-prototypes]
int set_direct_map_default_noflush(struct page *page)
^
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/1600222847-56792-1-git-send-email-tiantao6@hisilicon.com
arch/arm64/mm/pageattr.c:138:5: warning: no previous prototype for
arch/arm64/mm/pageattr.c:150:5: warning: no previous prototype for
arch/arm64/mm/pageattr.c:165:5: warning: no previous prototype for
Signed-off-by: Will Deacon <will@kernel.org>
Fix the following warnings.
arch/arm64/kernel/fpsimd.c:935:6: warning: no previous prototype for
‘do_sve_acc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:962:6: warning: no previous prototype for
‘do_fpsimd_acc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:971:6: warning: no previous prototype for
‘do_fpsimd_exc’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:1266:6: warning: no previous prototype for
‘kernel_neon_begin’ [-Wmissing-prototypes]
arch/arm64/kernel/fpsimd.c:1292:6: warning: no previous prototype for
‘kernel_neon_end’ [-Wmissing-prototypes]
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/1600157999-14802-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Will Deacon <will@kernel.org>
Leon Romanovsky says:
====================
This series from Alex extends software steering interface to support
devices with extra capability "sw_owner_2" which will replace existing
"sw_owner".
====================
Based on the mlx5-next branch at
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux
due to dependencies.
* branch 'mlx5_sw_owner_v2:
RDMA/mlx5: Expose TIR and QP ICM address for sw_owner_v2 devices
RDMA/mlx5: Allow DM allocation for sw_owner_v2 enabled devices
RDMA/mlx5: Add sw_owner_v2 bit capability
Leon Romanovsky says:
====================
IBTA declares speed as 16 bits, but kernel stores it in u8. This series
fixes in-kernel declaration while keeping external interface intact.
====================
Based on the mlx5-next branch at
git://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux
due to dependencies.
* branch 'mlx5_active_speed':
RDMA: Fix link active_speed size
RDMA/mlx5: Delete duplicated mlx5_ptys_width enum
net/mlx5: Refactor query port speed functions
According to the IB spec active_speed size should be u16 and not u8 as
before. Changing it to allow further extensions in offered speeds.
Link: https://lore.kernel.org/r/20200917090223.1018224-4-leon@kernel.org
Signed-off-by: Aharon Landau <aharonl@mellanox.com>
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Note that error handling on the result of a call to platform_get_resource()
is unneeded when the value is passed to devm_ioremap_resource(), so remove
it. Then use the helper function that wraps the calls to
platform_get_resource() and devm_ioremap_resource() together.
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Use the devm_platform_ioremap_resource_byname() helper instead of
calling platform_get_resource_byname() and devm_ioremap_resource()
separately.
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Rename the header guard of r4k-timer.h from __ASM_R4K_TYPES_H to
__ASM_R4K_TIMER_H what corresponding with the file name.
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Historically architectures have had duplicated code in their stack trace
implementations for filtering what gets traced. In order to avoid this
duplication some generic code has been provided using a new interface
arch_stack_walk(), enabled by selecting ARCH_STACKWALK in Kconfig, which
factors all this out into the generic stack trace code. Convert arm64
to use this common infrastructure.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20200914153409.25097-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
As with the generic arch_stack_walk() code the arm64 stack walk code takes
a callback that is called per stack frame. Currently the arm64 code always
passes a struct stackframe to the callback and the generic code just passes
the pc, however none of the users ever reference anything in the struct
other than the pc value. The arm64 code also uses a return type of int
while the generic code uses a return type of bool though in both cases the
return value is a boolean value and the sense is inverted between the two.
In order to reduce code duplication when arm64 is converted to use
arch_stack_walk() change the signature and return sense of the arm64
specific callback to match that of the generic code.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20200914153409.25097-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently the callback passed to arch_stack_walk() has an argument called
reliable passed to it to indicate if the stack entry is reliable, a comment
says that this is used by some printk() consumers. However in the current
kernel none of the arch_stack_walk() implementations ever set this flag to
true and the only callback implementation we have is in the generic
stacktrace code which ignores the flag. It therefore appears that this
flag is redundant so we can simplify and clarify things by removing it.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20200914153409.25097-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
They do get called from the #MC handler which is already marked
"noinstr".
Commit
e2def7d49d ("x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR")
already got rid of the instrumentation in the MSR accessors, fix the
annotation now too, in order to get rid of:
vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200915194020.28807-1-bp@alien8.de
While it is true that reading from an unmirrored source always uses
index 0, that is no longer true for mirrored sources when we fail over.
Fixes: 563c53e73b ("NFS: Fix flexfiles read failover")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Integrate the FP tests with the build system and add some documentation
for the ones run outside the kselftest infrastructure. The content in
the README was largely written by Dave Martin with edits by me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-7-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add wrapper scripts which invoke fpsimd-test and sve-test with several
copies per CPU such that the context switch code will be appropriately
exercised.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-6-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
vlset is a small utility for use in conjunction with tests like the sve-test
stress test which allows another executable to be invoked with a configured
SVE vector length.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add programs sve-test and fpsimd-test which spin reading and writing to
the SVE and FPSIMD registers, verifying the operations they perform. The
intended use is to leave them running to stress the context switch code's
handling of these registers which isn't compatible with what kselftest
does so they're not integrated into the framework but there's no other
obvious testsuite where they fit so let's store them here.
These tests were written by Dave Martin and lightly adapted by me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add a test case that does some basic verification of the SVE ptrace
interface, forking off a child with known values in the registers and
then using ptrace to inspect and manipulate the SVE registers of the
child, including in FPSIMD mode to account for sharing between the SVE
and FPSIMD registers.
This program was written by Dave Martin and modified for kselftest by
me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add a test case that verifies that we can enumerate the SVE vector lengths
on systems where we detect SVE, and that those SVE vector lengths are
valid. This program was written by Dave Martin and adapted to kselftest by
me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Submounts have their own superblock, which needs to be initialized.
However, they do not have a fuse_fs_context associated with them, and
the root node's attributes should be taken from the mountpoint's node.
Extend fuse_fill_super_common() to work for submounts by making the @ctx
parameter optional, and by adding a @submount_finode parameter.
(There is a plain "unsigned" in an existing code block that is being
indented by this commit. Extend it to "unsigned int" so checkpatch does
not complain.)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We want to allow submounts for the same fuse_conn, but with different
superblocks so that each of the submounts has its own device ID. To do
so, we need to split all mount-specific information off of fuse_conn
into a new fuse_mount structure, so that multiple mounts can share a
single fuse_conn.
We need to take care only to perform connection-level actions once (i.e.
when the fuse_conn and thus the first fuse_mount are established, or
when the last fuse_mount and thus the fuse_conn are destroyed). For
example, fuse_sb_destroy() must invoke fuse_send_destroy() until the
last superblock is released.
To do so, we keep track of which fuse_mount is the root mount and
perform all fuse_conn-level actions only when this fuse_mount is
involved.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
With the last commit, all functions that handle some existing fuse_req
no longer need to be given the associated fuse_conn, because they can
get it from the fuse_req object.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Every fuse_req belongs to a fuse_conn. Right now, we always know which
fuse_conn that is based on the respective device, but we want to allow
multiple (sub)mounts per single connection, and then the corresponding
filesystem is not going to be so trivial to obtain.
Storing a pointer to the associated fuse_conn in every fuse_req will
allow us to trivially find any request's superblock (and thus
filesystem) even then.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
- Add fuse_attr.flags
- Add FUSE_ATTR_SUBMOUNT
This is a flag for fuse_attr.flags that indicates that the given entry
resides on a different filesystem than the parent, and as such should
have a different st_dev.
- Add FUSE_SUBMOUNTS
The client sets this flag if it supports automounting directories.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
PAuth adds 5 different keys that can be used to sign addresses.
Add a test that verifies that the kernel initializes them to different
values and preserves them across context switches.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200918104715.182310-5-boian4o1@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
Kernel documentation states that it will change PAuth keys on exec() calls.
Verify that all keys are correctly switched to new ones.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200918104715.182310-4-boian4o1@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
PAuth adds sign/verify controls to enable and disable groups of
instructions in hardware for compatibility with libraries that do not
implement PAuth. The kernel always enables them if it detects PAuth.
Add a test that checks that each group of instructions is enabled, if the
kernel reports PAuth as detected.
Note: For groups, for the purpose of this patch, we intend instructions
that use a certain key.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200918104715.182310-3-boian4o1@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
PAuth signs and verifies return addresses on the stack. It does so by
inserting a Pointer Authentication code (PAC) into some of the unused top
bits of an address. This is achieved by adding paciasp/autiasp instructions
at the beginning and end of a function.
This feature is partially backwards compatible with earlier versions of the
ARM architecture. To coerce the compiler into emitting fully backwards
compatible code the main file is compiled to target an earlier ARM version.
This allows the tests to check for the feature and print meaningful error
messages instead of crashing.
Add a test to verify that corrupting the return address results in a
SIGSEGV on return.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200918104715.182310-2-boian4o1@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
This change exposes write-combine mappings under sysfs for
prefetchable PCI resources on arm64.
Originally, the usage of "write combine" here was driven by the x86
definition of write combine. This definition is specific to x86 and
does not generalize to other architectures. However, the usage of WC
has mutated to "write combine" semantics, which is implemented
differently on each arch.
Generally, prefetchable BARs are accepted to allow speculative
accesses, write combining, and re-ordering-- from the PCI perspective,
this means there are no read side effects. (This contradicts the PCI
spec which allows prefetchable BARs to have read side effects, but
this definition is ill-advised as it is impossible to meet.) On x86,
prefetchable BARs are mapped as WC as originally defined (with some
conditionals on arch features). On arm64, WC is taken to mean normal
non-cacheable memory.
In practice, write combine semantics are used to minimize write
operations. A common usage of this is minimizing PCI TLPs which can
significantly improve performance with PCI devices. In order to
provide the same benefits to userspace, we need to allow userspace to
map prefetchable BARs with write combine semantics. The resourceX_wc
mapping is used today by userspace programs and libraries.
While this model is flawed as "write combine" is very ill-defined, it
is already used by multiple non-x86 archs to expose write combine
semantics to user space. We enable this on arm64 to give userspace on
arm64 an equivalent mechanism for utilizing write combining with PCI
devices.
Signed-off-by: Clint Sbisa <csbisa@amazon.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200918033312.ddfpibgfylfjpex2@amazon.com
Signed-off-by: Will Deacon <will@kernel.org>
