diff options
| author | Ben Horgan <ben.horgan@arm.com> | 2025-05-12 12:41:10 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2025-05-16 13:01:18 +0100 |
| commit | 5799a2983fea4f22f6aaa291aee3b704db81d29f (patch) | |
| tree | 1ac740611c31a83a593a592a5e865315524fac60 | |
| parent | 9c32cda43eb78f78c73aee4aa344b777714e259b (diff) | |
arm64/sysreg: Expose MTE_frac so that it is visible to KVM
KVM exposes the sanitised ID registers to guests. Currently these ignore
the ID_AA64PFR1_EL1.MTE_frac field, meaning guests always see a value of
zero.
This is a problem for platforms without the MTE_ASYNC feature where
ID_AA64PFR1_EL1.MTE==0x2 and ID_AA64PFR1_EL1.MTE_frac==0xf. KVM forces
MTE_frac to zero, meaning the guest believes MTE_ASYNC is supported, when
no async fault will ever occur.
Before KVM can fix this, the architecture needs to sanitise the ID
register field for MTE_frac.
Linux itself does not use MTE_frac field and just assumes MTE async faults
can be generated if MTE is supported.
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Link: https://lore.kernel.org/r/20250512114112.359087-2-ben.horgan@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/kernel/cpufeature.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 9c4d6d552b25..e952f4b07ce1 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -298,6 +298,7 @@ static const struct arm64_ftr_bits ftr_id_aa64pfr0[] = { static const struct arm64_ftr_bits ftr_id_aa64pfr1[] = { ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_GCS), FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_GCS_SHIFT, 4, 0), + S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_MTE_frac_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_SME), FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_SME_SHIFT, 4, 0), ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64PFR1_EL1_MPAM_frac_SHIFT, 4, 0), |