Commit 17601bfe authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option 



In order to differenciate between architectures that require no extra
synchronisation when accessing the dirty ring and those who do,
add a new capability (KVM_CAP_DIRTY_LOG_RING_ACQ_REL) that identify
the latter sort. TSO architectures can obviously advertise both, while
relaxed architectures must only advertise the ACQ_REL version.

This requires some configuration symbol rejigging, with HAVE_KVM_DIRTY_RING
being only indirectly selected by two top-level config symbols:
- HAVE_KVM_DIRTY_RING_TSO for strongly ordered architectures (x86)
- HAVE_KVM_DIRTY_RING_ACQ_REL for weakly ordered architectures (arm64)

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20220926145120.27974-3-maz@kernel.org
parent 8929bc96

arch/x86/kvm/Kconfig

+1 −1
Original line number Original line Diff line number Diff line
@@ -28,7 +28,7 @@ config KVM 
	select HAVE_KVM_IRQCHIP

	select HAVE_KVM_IRQCHIP

	select HAVE_KVM_PFNCACHE

	select HAVE_KVM_PFNCACHE

	select HAVE_KVM_IRQFD

	select HAVE_KVM_IRQFD

	select HAVE_KVM_DIRTY_RING

	select HAVE_KVM_DIRTY_RING_TSO

	select IRQ_BYPASS_MANAGER

	select IRQ_BYPASS_MANAGER

	select HAVE_KVM_IRQ_BYPASS

	select HAVE_KVM_IRQ_BYPASS

	select HAVE_KVM_IRQ_ROUTING

	select HAVE_KVM_IRQ_ROUTING

include/uapi/linux/kvm.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -1177,6 +1177,7 @@ struct kvm_ppc_resize_hpt { 
#define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 220

#define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 220

#define KVM_CAP_S390_ZPCI_OP 221

#define KVM_CAP_S390_ZPCI_OP 221

#define KVM_CAP_S390_CPU_TOPOLOGY 222

#define KVM_CAP_S390_CPU_TOPOLOGY 222

#define KVM_CAP_DIRTY_LOG_RING_ACQ_REL 223





#ifdef KVM_CAP_IRQ_ROUTING

#ifdef KVM_CAP_IRQ_ROUTING

virt/kvm/Kconfig

+14 −0
Original line number Original line Diff line number Diff line
@@ -19,6 +19,20 @@ config HAVE_KVM_IRQ_ROUTING 
config HAVE_KVM_DIRTY_RING

config HAVE_KVM_DIRTY_RING

       bool

       bool





# Only strongly ordered architectures can select this, as it doesn't

# put any explicit constraint on userspace ordering. They can also

# select the _ACQ_REL version.

config HAVE_KVM_DIRTY_RING_TSO

       bool

       select HAVE_KVM_DIRTY_RING

       depends on X86



# Weakly ordered architectures can only select this, advertising

# to userspace the additional ordering requirements.

config HAVE_KVM_DIRTY_RING_ACQ_REL

       bool

       select HAVE_KVM_DIRTY_RING



config HAVE_KVM_EVENTFD

config HAVE_KVM_EVENTFD

       bool

       bool

       select EVENTFD

       select EVENTFD

virt/kvm/kvm_main.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -4475,7 +4475,13 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) 
	case KVM_CAP_NR_MEMSLOTS:

	case KVM_CAP_NR_MEMSLOTS:

		return KVM_USER_MEM_SLOTS;

		return KVM_USER_MEM_SLOTS;

	case KVM_CAP_DIRTY_LOG_RING:

	case KVM_CAP_DIRTY_LOG_RING:

#ifdef CONFIG_HAVE_KVM_DIRTY_RING

#ifdef CONFIG_HAVE_KVM_DIRTY_RING_TSO

		return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);

#else

		return 0;

#endif

	case KVM_CAP_DIRTY_LOG_RING_ACQ_REL:

#ifdef CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL

		return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);

		return KVM_DIRTY_RING_MAX_ENTRIES * sizeof(struct kvm_dirty_gfn);

#else

#else

		return 0;

		return 0;
@@ -4580,6 +4586,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, 
		return 0;

		return 0;

	}

	}

	case KVM_CAP_DIRTY_LOG_RING:

	case KVM_CAP_DIRTY_LOG_RING:

	case KVM_CAP_DIRTY_LOG_RING_ACQ_REL:

		return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]);

		return kvm_vm_ioctl_enable_dirty_log_ring(kvm, cap->args[0]);

	default:

	default:

		return kvm_vm_ioctl_enable_cap(kvm, cap);

		return kvm_vm_ioctl_enable_cap(kvm, cap);