Messages in this thread | | | Subject | Re: [PATCH V3 02/16] arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register | From | Anshuman Khandual <> | Date | Tue, 5 May 2020 12:20:41 +0530 |
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On 05/05/2020 01:54 AM, Will Deacon wrote: > On Sat, May 02, 2020 at 07:03:51PM +0530, Anshuman Khandual wrote: >> ID_DFR0 based TraceFilt feature should not be exposed to guests. Hence lets >> drop it. >> >> Cc: Catalin Marinas <catalin.marinas@arm.com> >> Cc: Will Deacon <will@kernel.org> >> Cc: Marc Zyngier <maz@kernel.org> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: James Morse <james.morse@arm.com> >> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> >> Suggested-by: Mark Rutland <mark.rutland@arm.com> >> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >> --- >> arch/arm64/kernel/cpufeature.c | 1 - >> 1 file changed, 1 deletion(-) >> >> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c >> index 6d032fbe416f..51386dade423 100644 >> --- a/arch/arm64/kernel/cpufeature.c >> +++ b/arch/arm64/kernel/cpufeature.c >> @@ -435,7 +435,6 @@ static const struct arm64_ftr_bits ftr_id_pfr1[] = { >> }; >> >> static const struct arm64_ftr_bits ftr_id_dfr0[] = { >> - ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, 28, 4, 0), > > Hmm, this still confuses me. Is this not now FTR_NONSTRICT? Why is that ok?
Mark had mentioned about it earlier (https://patchwork.kernel.org/patch/11287805/) Did I misinterpret the first part ? Could not figure "capping the emulated debug features" part. Probably, Mark could give some more details.
From the earlier discussion:
* ID_DFR0 fields need more thought; we should limit what we expose here. I don't think it's valid for us to expose TraceFilt, and I suspect we need to add capping for debug features we currently emulate.
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