Commit 96906a91 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Expose {un,}lock_all_vcpus() to the rest of KVM 



Being able to lock/unlock all vcpus in one go is a feature that
only the vgic has enjoyed so far. Let's be brave and expose it
to the world.

Reviewed-by: default avatarColton Lewis <coltonlewis@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-7-maz@kernel.org
parent c605ee24

arch/arm64/include/asm/kvm_host.h

+3 −0
Original line number Diff line number Diff line
@@ -922,6 +922,9 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu); 


int __init kvm_sys_reg_table_init(void);



bool lock_all_vcpus(struct kvm *kvm);

void unlock_all_vcpus(struct kvm *kvm);



/* MMIO helpers */

void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);

unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);

arch/arm64/kvm/arm.c

+43 −0
Original line number Diff line number Diff line
@@ -1484,6 +1484,49 @@ long kvm_arch_vm_ioctl(struct file *filp, 
	}

}



/* unlocks vcpus from @vcpu_lock_idx and smaller */

static void unlock_vcpus(struct kvm *kvm, int vcpu_lock_idx)

{

	struct kvm_vcpu *tmp_vcpu;



	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {

		tmp_vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);

		mutex_unlock(&tmp_vcpu->mutex);

	}

}



void unlock_all_vcpus(struct kvm *kvm)

{

	lockdep_assert_held(&kvm->lock);



	unlock_vcpus(kvm, atomic_read(&kvm->online_vcpus) - 1);

}



/* Returns true if all vcpus were locked, false otherwise */

bool lock_all_vcpus(struct kvm *kvm)

{

	struct kvm_vcpu *tmp_vcpu;

	unsigned long c;



	lockdep_assert_held(&kvm->lock);



	/*

	 * Any time a vcpu is in an ioctl (including running), the

	 * core KVM code tries to grab the vcpu->mutex.

	 *

	 * By grabbing the vcpu->mutex of all VCPUs we ensure that no

	 * other VCPUs can fiddle with the state while we access it.

	 */

	kvm_for_each_vcpu(c, tmp_vcpu, kvm) {

		if (!mutex_trylock(&tmp_vcpu->mutex)) {

			unlock_vcpus(kvm, c - 1);

			return false;

		}

	}



	return true;

}



static unsigned long nvhe_percpu_size(void)

{

	return (unsigned long)CHOOSE_NVHE_SYM(__per_cpu_end) -

arch/arm64/kvm/vgic/vgic-kvm-device.c

+0 −38
Original line number Diff line number Diff line
@@ -342,44 +342,6 @@ int vgic_v2_parse_attr(struct kvm_device *dev, struct kvm_device_attr *attr, 
	return 0;

}



/* unlocks vcpus from @vcpu_lock_idx and smaller */

static void unlock_vcpus(struct kvm *kvm, int vcpu_lock_idx)

{

	struct kvm_vcpu *tmp_vcpu;



	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {

		tmp_vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);

		mutex_unlock(&tmp_vcpu->mutex);

	}

}



void unlock_all_vcpus(struct kvm *kvm)

{

	unlock_vcpus(kvm, atomic_read(&kvm->online_vcpus) - 1);

}



/* Returns true if all vcpus were locked, false otherwise */

bool lock_all_vcpus(struct kvm *kvm)

{

	struct kvm_vcpu *tmp_vcpu;

	unsigned long c;



	/*

	 * Any time a vcpu is run, vcpu_load is called which tries to grab the

	 * vcpu->mutex.  By grabbing the vcpu->mutex of all VCPUs we ensure

	 * that no other VCPUs are run and fiddle with the vgic state while we

	 * access it.

	 */

	kvm_for_each_vcpu(c, tmp_vcpu, kvm) {

		if (!mutex_trylock(&tmp_vcpu->mutex)) {

			unlock_vcpus(kvm, c - 1);

			return false;

		}

	}



	return true;

}



/**

 * vgic_v2_attr_regs_access - allows user space to access VGIC v2 state

 *

arch/arm64/kvm/vgic/vgic.h

+0 −3
Original line number Diff line number Diff line
@@ -273,9 +273,6 @@ int vgic_init(struct kvm *kvm); 
void vgic_debug_init(struct kvm *kvm);

void vgic_debug_destroy(struct kvm *kvm);



bool lock_all_vcpus(struct kvm *kvm);

void unlock_all_vcpus(struct kvm *kvm);



static inline int vgic_v3_max_apr_idx(struct kvm_vcpu *vcpu)

{

	struct vgic_cpu *cpu_if = &vcpu->arch.vgic_cpu;