Commit 8823485a authored by Fuad Tabba's avatar Fuad Tabba Committed by Marc Zyngier
Browse files

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



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: default avatarOliver Upton <oupton@kernel.org>
Signed-off-by: default avatarFuad 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: default avatarMarc Zyngier <maz@kernel.org>
parent f4eee308

arch/arm64/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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__ */

arch/arm64/kvm/arm.c

+45 −0
Original line number Diff line number Diff line
@@ -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);