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KVM: arm64: PSCI: Forbid 64bit functions for 32bit guests

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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>
This commit is contained in:
Marc Zyngier 2020-04-01 12:38:49 +01:00
parent 2890ac993d
commit fdc9999e20
1 changed files with 24 additions and 0 deletions
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24
virt/kvm/arm/psci.c
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@ -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: