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| author | Stephen Boyd <swboyd@chromium.org> | 2020-10-23 18:47:50 +0300 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2020-10-28 14:13:36 +0300 |
| commit | 1de111b51b829bcf01d2e57971f8fd07a665fa3f (patch) | |
| tree | 5cda2f8e9d72df562ebfdd7fff4fd0556b11306e /include/linux/arm-smccc.h | |
| parent | 0fa97e9403c767a4af63cfb5a3badbbe69426085 (diff) | |
| download | linux-1de111b51b829bcf01d2e57971f8fd07a665fa3f.tar.xz | |
KVM: arm64: ARM_SMCCC_ARCH_WORKAROUND_1 doesn't return SMCCC_RET_NOT_REQUIRED
According to the SMCCC spec[1](7.5.2 Discovery) the
ARM_SMCCC_ARCH_WORKAROUND_1 function id only returns 0, 1, and
SMCCC_RET_NOT_SUPPORTED.
0 is "workaround required and safe to call this function"
1 is "workaround not required but safe to call this function"
SMCCC_RET_NOT_SUPPORTED is "might be vulnerable or might not be, who knows, I give up!"
SMCCC_RET_NOT_SUPPORTED might as well mean "workaround required, except
calling this function may not work because it isn't implemented in some
cases". Wonderful. We map this SMC call to
0 is SPECTRE_MITIGATED
1 is SPECTRE_UNAFFECTED
SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE
For KVM hypercalls (hvc), we've implemented this function id to return
SMCCC_RET_NOT_SUPPORTED, 0, and SMCCC_RET_NOT_REQUIRED. One of those
isn't supposed to be there. Per the code we call
arm64_get_spectre_v2_state() to figure out what to return for this
feature discovery call.
0 is SPECTRE_MITIGATED
SMCCC_RET_NOT_REQUIRED is SPECTRE_UNAFFECTED
SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE
Let's clean this up so that KVM tells the guest this mapping:
0 is SPECTRE_MITIGATED
1 is SPECTRE_UNAFFECTED
SMCCC_RET_NOT_SUPPORTED is SPECTRE_VULNERABLE
Note: SMCCC_RET_NOT_AFFECTED is 1 but isn't part of the SMCCC spec
Fixes: c118bbb52743 ("arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://developer.arm.com/documentation/den0028/latest [1]
Link: https://lore.kernel.org/r/20201023154751.1973872-1-swboyd@chromium.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'include/linux/arm-smccc.h')
| -rw-r--r-- | include/linux/arm-smccc.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h index 885c9ffc835c..f860645f6512 100644 --- a/include/linux/arm-smccc.h +++ b/include/linux/arm-smccc.h @@ -87,6 +87,8 @@ ARM_SMCCC_SMC_32, \ 0, 0x7fff) +#define SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED 1 + /* Paravirtualised time calls (defined by ARM DEN0057A) */ #define ARM_SMCCC_HV_PV_TIME_FEATURES \ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \ |