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| author | Marc Zyngier <maz@kernel.org> | 2020-04-01 12:38:49 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2020-04-17 09:51:45 +0100 |
| commit | fdc9999e20cd038d9d5bf54496c1f0226bc2b64e (patch) | |
| tree | 905fb6601f8580c9fc5434d81ffd3a766e03cba1 /virt/kvm | |
| parent | 2890ac993daa7bdcc57a92da2f07bcdec243666b (diff) | |
| download | lwn-fdc9999e20cd038d9d5bf54496c1f0226bc2b64e.tar.gz lwn-fdc9999e20cd038d9d5bf54496c1f0226bc2b64e.zip | |
KVM: arm64: PSCI: Forbid 64bit functions for 32bit guests
Implementing (and even advertising) 64bit PSCI functions to 32bit
guests is at least a bit odd, if not altogether violating the
spec which says ("5.2.1 Register usage in arguments and return values"):
"Adherence to the SMC Calling Conventions implies that any AArch32
caller of an SMC64 function will get a return code of 0xFFFFFFFF(int32).
This matches the NOT_SUPPORTED error code used in PSCI"
Tighten the implementation by pretending these functions are not
there for 32bit guests.
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/arm/psci.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c index 3772717efe3e..ae364716ee40 100644 --- a/virt/kvm/arm/psci.c +++ b/virt/kvm/arm/psci.c @@ -198,6 +198,21 @@ static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu) vcpu_set_reg(vcpu, i, lower_32_bits(vcpu_get_reg(vcpu, i))); } +static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn) +{ + switch(fn) { + case PSCI_0_2_FN64_CPU_SUSPEND: + case PSCI_0_2_FN64_CPU_ON: + case PSCI_0_2_FN64_AFFINITY_INFO: + /* Disallow these functions for 32bit guests */ + if (vcpu_mode_is_32bit(vcpu)) + return PSCI_RET_NOT_SUPPORTED; + break; + } + + return 0; +} + static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) { struct kvm *kvm = vcpu->kvm; @@ -205,6 +220,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) unsigned long val; int ret = 1; + val = kvm_psci_check_allowed_function(vcpu, psci_fn); + if (val) + goto out; + switch (psci_fn) { case PSCI_0_2_FN_PSCI_VERSION: /* @@ -272,6 +291,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) break; } +out: smccc_set_retval(vcpu, val, 0, 0, 0); return ret; } @@ -289,6 +309,10 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu) break; case PSCI_1_0_FN_PSCI_FEATURES: feature = smccc_get_arg1(vcpu); + val = kvm_psci_check_allowed_function(vcpu, feature); + if (val) + break; + switch(feature) { case PSCI_0_2_FN_PSCI_VERSION: case PSCI_0_2_FN_CPU_SUSPEND: |