diff options
| author | Rob Herring <robh@kernel.org> | 2020-10-28 13:28:39 -0500 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-10-29 12:56:01 +0000 |
| commit | 96d389ca10110d7eefb46feb6af9a0c6832f78f5 (patch) | |
| tree | 100d4c5967acc6b8eab520466073417b4e3b52fa /arch/arm64/kernel | |
| parent | 8a6b88e66233f5f1779b0a1342aa9dc030dddcd5 (diff) | |
arm64: Add workaround for Arm Cortex-A77 erratum 1508412
On Cortex-A77 r0p0 and r1p0, a sequence of a non-cacheable or device load
and a store exclusive or PAR_EL1 read can cause a deadlock.
The workaround requires a DMB SY before and after a PAR_EL1 register
read. In addition, it's possible an interrupt (doing a device read) or
KVM guest exit could be taken between the DMB and PAR read, so we
also need a DMB before returning from interrupt and before returning to
a guest.
A deadlock is still possible with the workaround as KVM guests must also
have the workaround. IOW, a malicious guest can deadlock an affected
systems.
This workaround also depends on a firmware counterpart to enable the h/w
to insert DMB SY after load and store exclusive instructions. See the
errata document SDEN-1152370 v10 [1] for more information.
[1] https://static.docs.arm.com/101992/0010/Arm_Cortex_A77_MP074_Software_Developer_Errata_Notice_v10.pdf
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: kvmarm@lists.cs.columbia.edu
Link: https://lore.kernel.org/r/20201028182839.166037-2-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/cpu_errata.c | 10 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 3 |
2 files changed, 13 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c index 24d75af344b1..61314fd70f13 100644 --- a/arch/arm64/kernel/cpu_errata.c +++ b/arch/arm64/kernel/cpu_errata.c @@ -523,6 +523,16 @@ const struct arm64_cpu_capabilities arm64_errata[] = { .cpu_enable = cpu_enable_trap_ctr_access, }, #endif +#ifdef CONFIG_ARM64_ERRATUM_1508412 + { + /* we depend on the firmware portion for correctness */ + .desc = "ARM erratum 1508412 (kernel portion)", + .capability = ARM64_WORKAROUND_1508412, + ERRATA_MIDR_RANGE(MIDR_CORTEX_A77, + 0, 0, + 1, 0), + }, +#endif { } }; diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index f30007dff35f..b295fb912b12 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -365,6 +365,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 br x30 #endif .else + /* Ensure any device/NC reads complete */ + alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 + eret .endif sb |