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KVM: arm64: Convert ARCH_WORKAROUND_2 to arm64_get_spectre_v4_state()

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Convert the KVM WA2 code to using the Spectre infrastructure,
making the code much more readable. It also allows us to
take SSBS into account for the mitigation.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Marc Zyngier 2020-09-18 14:08:54 +01:00 committed by Will Deacon
parent 7311467702
commit d63d975a71
3 changed files with 30 additions and 14 deletions
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2
arch/arm64/kvm/arm.c
View File

@ -1292,7 +1292,7 @@ static void cpu_init_hyp_mode(void)
* at EL2.
*/
if (this_cpu_has_cap(ARM64_SSBS) &&
arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE) {
arm64_get_spectre_v4_state() == SPECTRE_VULNERABLE) {
kvm_call_hyp_nvhe(__kvm_enable_ssbs);
}
}

23
arch/arm64/kvm/hypercalls.c
View File

@ -36,13 +36,24 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
}
break;
case ARM_SMCCC_ARCH_WORKAROUND_2:
switch (arm64_get_ssbd_state()) {
case ARM64_SSBD_FORCE_DISABLE:
case ARM64_SSBD_UNKNOWN:
switch (arm64_get_spectre_v4_state()) {
case SPECTRE_VULNERABLE:
break;
case ARM64_SSBD_KERNEL:
case ARM64_SSBD_FORCE_ENABLE:
case ARM64_SSBD_MITIGATED:
case SPECTRE_MITIGATED:
/*
* SSBS everywhere: Indicate no firmware
* support, as the SSBS support will be
* indicated to the guest and the default is
* safe.
*
* Otherwise, expose a permanent mitigation
* to the guest, and hide SSBS so that the
* guest stays protected.
*/
if (cpus_have_final_cap(ARM64_SSBS))
break;
fallthrough;
case SPECTRE_UNAFFECTED:
val = SMCCC_RET_NOT_REQUIRED;
break;
}

19
arch/arm64/kvm/psci.c
View File

@ -435,14 +435,19 @@ static int get_kernel_wa_level(u64 regid)
}
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
switch (arm64_get_ssbd_state()) {
case ARM64_SSBD_FORCE_ENABLE:
case ARM64_SSBD_MITIGATED:
case ARM64_SSBD_KERNEL:
switch (arm64_get_spectre_v4_state()) {
case SPECTRE_MITIGATED:
/*
* As for the hypercall discovery, we pretend we
* don't have any FW mitigation if SSBS is there at
* all times.
*/
if (cpus_have_final_cap(ARM64_SSBS))
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
fallthrough;
case SPECTRE_UNAFFECTED:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
case ARM64_SSBD_UNKNOWN:
case ARM64_SSBD_FORCE_DISABLE:
default:
case SPECTRE_VULNERABLE:
return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
}
}