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KVM: arm64: Add generic check for system-supported vCPU features

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To date KVM has relied on kvm_reset_vcpu() failing when the vCPU feature
flags are unsupported by the system. This is a bit messy since
kvm_reset_vcpu() is called at runtime outside of the KVM_ARM_VCPU_INIT
ioctl when it is expected to succeed. Further complicating the matter is
that kvm_reset_vcpu() must tolerate be idemptotent to the config_lock,
as it isn't consistently called with the lock held.

Prepare to move feature compatibility checks out of kvm_reset_vcpu() with
a 'generic' check that compares the user-provided flags with a computed
maximum feature set for the system.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/20230920195036.1169791-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton 2023-09-20 19:50:29 +00:00
parent ce9ecca023
commit ef150908b6
1 changed files with 13 additions and 3 deletions
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16
arch/arm64/kvm/arm.c
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@ -1190,6 +1190,16 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
return -EINVAL;
}
static unsigned long system_supported_vcpu_features(void)
{
unsigned long features = KVM_VCPU_VALID_FEATURES;
if (!cpus_have_final_cap(ARM64_HAS_32BIT_EL1))
clear_bit(KVM_ARM_VCPU_EL1_32BIT, &features);
return features;
}
static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu,
const struct kvm_vcpu_init *init)
{
@ -1204,12 +1214,12 @@ static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu,
return -ENOENT;
}
if (features & ~system_supported_vcpu_features())
return -EINVAL;
if (!test_bit(KVM_ARM_VCPU_EL1_32BIT, &features))
return 0;
if (!cpus_have_const_cap(ARM64_HAS_32BIT_EL1))
return -EINVAL;
/* MTE is incompatible with AArch32 */
if (kvm_has_mte(vcpu->kvm))
return -EINVAL;