diff options
| author | Marc Zyngier <maz@kernel.org> | 2022-09-26 15:51:16 +0100 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2022-09-29 10:23:08 +0100 |
| commit | 17601bfed909fa080fcfd227b57da2bd4dc2d2a6 (patch) | |
| tree | 79e7babcef9a32617591bd2147206b00dab25714 /virt/kvm | |
| parent | 8929bc9659640f35dd2ef8373263cbd885b4a072 (diff) | |
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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20220926145120.27974-3-maz@kernel.org
Diffstat (limited to 'virt/kvm')
| -rw-r--r-- | virt/kvm/Kconfig | 14 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 9 |
2 files changed, 22 insertions, 1 deletions
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig index a8c5c9f06b3c..800f9470e36b 100644 --- a/virt/kvm/Kconfig +++ b/virt/kvm/Kconfig @@ -19,6 +19,20 @@ config HAVE_KVM_IRQ_ROUTING config HAVE_KVM_DIRTY_RING 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 bool select EVENTFD diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 584a5bab3af3..5b064dbadaf4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4475,7 +4475,13 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_NR_MEMSLOTS: return KVM_USER_MEM_SLOTS; 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); #else return 0; @@ -4580,6 +4586,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, return 0; } 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]); default: return kvm_vm_ioctl_enable_cap(kvm, cap); |