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KVM: arm64: Track KVM IOCTLs and their associated KVM caps

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Track KVM IOCTLs (VM IOCTLs for now), and the associated KVM capability
that enables that IOCTL. Add a function that performs the lookup.

This will be used by CoCo VM Hypervisors (e.g., pKVM) to determine
whether a particular KVM IOCTL is allowed for its VMs.

Suggested-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
[maz: don't expose KVM_CAP_BASIC to userspace, and rely on NR_VCPUS
      as a proxy for this]
Link: https://patch.msgid.link/20251211104710.151771-8-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Fuad Tabba 2025-12-11 10:47:07 +00:00 committed by Marc Zyngier
parent f4eee308c8
commit 8823485a69
2 changed files with 47 additions and 0 deletions
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2
arch/arm64/include/asm/kvm_host.h
View File

@ -1655,4 +1655,6 @@ static __always_inline enum fgt_group_id __fgt_reg_to_group_id(enum vcpu_sysreg
p; \
})
long kvm_get_cap_for_kvm_ioctl(unsigned int ioctl, long *ext);
#endif /* __ARM64_KVM_HOST_H__ */

45
arch/arm64/kvm/arm.c
View File

@ -58,6 +58,51 @@ enum kvm_wfx_trap_policy {
static enum kvm_wfx_trap_policy kvm_wfi_trap_policy __read_mostly = KVM_WFX_NOTRAP_SINGLE_TASK;
static enum kvm_wfx_trap_policy kvm_wfe_trap_policy __read_mostly = KVM_WFX_NOTRAP_SINGLE_TASK;
/*
* Tracks KVM IOCTLs and their associated KVM capabilities.
*/
struct kvm_ioctl_cap_map {
unsigned int ioctl;
long ext;
};
/* Make KVM_CAP_NR_VCPUS the reference for features we always supported */
#define KVM_CAP_ARM_BASIC KVM_CAP_NR_VCPUS
/*
* Sorted by ioctl to allow for potential binary search,
* though linear scan is sufficient for this size.
*/
static const struct kvm_ioctl_cap_map vm_ioctl_caps[] = {
{ KVM_CREATE_IRQCHIP, KVM_CAP_IRQCHIP },
{ KVM_ARM_SET_DEVICE_ADDR, KVM_CAP_ARM_SET_DEVICE_ADDR },
{ KVM_ARM_MTE_COPY_TAGS, KVM_CAP_ARM_MTE },
{ KVM_SET_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
{ KVM_GET_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
{ KVM_HAS_DEVICE_ATTR, KVM_CAP_DEVICE_CTRL },
{ KVM_ARM_SET_COUNTER_OFFSET, KVM_CAP_COUNTER_OFFSET },
{ KVM_ARM_GET_REG_WRITABLE_MASKS, KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES },
{ KVM_ARM_PREFERRED_TARGET, KVM_CAP_ARM_BASIC },
};
/*
* Set *ext to the capability.
* Return 0 if found, or -EINVAL if no IOCTL matches.
*/
long kvm_get_cap_for_kvm_ioctl(unsigned int ioctl, long *ext)
{
int i;
for (i = 0; i < ARRAY_SIZE(vm_ioctl_caps); i++) {
if (vm_ioctl_caps[i].ioctl == ioctl) {
*ext = vm_ioctl_caps[i].ext;
return 0;
}
}
return -EINVAL;
}
DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base);