On Fri, Feb 05, 2021 at 05:41:05PM +0000, Suzuki K Poulose wrote:
On 2/4/21 9:54 AM, Will Deacon wrote:
On Wed, Feb 03, 2021 at 11:00:57PM +0000, Suzuki K Poulose wrote:
The erratum 1024718 affects Cortex-A55 r0p0 to r2p0. However we apply the work around for r0p0 - r1p0. Unfortunately this won't be fixed for the future revisions for the CPU. Thus extend the work around for all versions of A55, to cover for r2p0 and any future revisions.
Cc: stable@vger.kernel.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: James Morse james.morse@arm.com Cc: Kunihiko Hayashi hayashi.kunihiko@socionext.com Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com
arch/arm64/kernel/cpufeature.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index e99eddec0a46..db400ca77427 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1455,7 +1455,7 @@ static bool cpu_has_broken_dbm(void) /* List of CPUs which have broken DBM support. */ static const struct midr_range cpus[] = { #ifdef CONFIG_ARM64_ERRATUM_1024718
MIDR_RANGE(MIDR_CORTEX_A55, 0, 0, 1, 0), // A55 r0p0 -r1p0
MIDR_ALL_VERSIONS(MIDR_CORTEX_A55),I think we have bigger problems with this erratum, since cpu_has_hw_af() doesn't taken this erratum into account at all, meaning that arch_faults_on_old_pte() will return the wrong value on any system with an A55.
Please note that we enable HW_AF on these CPUs even with this erratum as they are not affected. It is only the DBM that we selectively disable. Thus the AF flag checks are still valid (See __cpu_setup in arch/arm64/mm/proc.S). Or am I miss something ?
Thanks, you're completely right! I'll queue this one then, and update the Kconfig test at the same time.
Will