Commit fdc9999e authored by Marc Zyngier's avatar Marc Zyngier

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: default avatarChristoffer Dall <christoffer.dall@arm.com>
Reviewed-by: default avatarAlexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 2890ac99
...@@ -198,6 +198,21 @@ static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu) ...@@ -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))); 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) static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{ {
struct kvm *kvm = vcpu->kvm; struct kvm *kvm = vcpu->kvm;
...@@ -205,6 +220,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) ...@@ -205,6 +220,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
unsigned long val; unsigned long val;
int ret = 1; int ret = 1;
val = kvm_psci_check_allowed_function(vcpu, psci_fn);
if (val)
goto out;
switch (psci_fn) { switch (psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION: case PSCI_0_2_FN_PSCI_VERSION:
/* /*
...@@ -272,6 +291,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) ...@@ -272,6 +291,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
break; break;
} }
out:
smccc_set_retval(vcpu, val, 0, 0, 0); smccc_set_retval(vcpu, val, 0, 0, 0);
return ret; return ret;
} }
...@@ -289,6 +309,10 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu) ...@@ -289,6 +309,10 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
break; break;
case PSCI_1_0_FN_PSCI_FEATURES: case PSCI_1_0_FN_PSCI_FEATURES:
feature = smccc_get_arg1(vcpu); feature = smccc_get_arg1(vcpu);
val = kvm_psci_check_allowed_function(vcpu, feature);
if (val)
break;
switch(feature) { switch(feature) {
case PSCI_0_2_FN_PSCI_VERSION: case PSCI_0_2_FN_PSCI_VERSION:
case PSCI_0_2_FN_CPU_SUSPEND: case PSCI_0_2_FN_CPU_SUSPEND:
......
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