From: Peter Xu <peterx@redhat.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>,
peterx@redhat.com, Andrew Jones <drjones@redhat.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH v15 06/14] KVM: Make dirty ring exclusive to dirty bitmap log
Date: Fri, 23 Oct 2020 14:33:50 -0400 [thread overview]
Message-ID: <20201023183358.50607-7-peterx@redhat.com> (raw)
In-Reply-To: <20201023183358.50607-1-peterx@redhat.com>
There's no good reason to use both the dirty bitmap logging and the
new dirty ring buffer to track dirty bits. We should be able to even
support both of them at the same time, but it could complicate things
which could actually help little. Let's simply make it the rule
before we enable dirty ring on any arch, that we don't allow these two
interfaces to be used together.
The big world switch would be KVM_CAP_DIRTY_LOG_RING capability
enablement. That's where we'll switch from the default dirty logging
way to the dirty ring way. As long as kvm->dirty_ring_size is setup
correctly, we'll once and for all switch to the dirty ring buffer mode
for the current virtual machine.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
Documentation/virt/kvm/api.rst | 7 +++++++
virt/kvm/kvm_main.c | 12 ++++++++++++
2 files changed, 19 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 00da3f01d632..33e393759444 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6507,3 +6507,10 @@ make sure all the existing dirty gfns are flushed to the dirty rings.
The dirty ring can gets full. When it happens, the KVM_RUN of the
vcpu will return with exit reason KVM_EXIT_DIRTY_LOG_FULL.
+
+NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding
+ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctl
+KVM_GET_DIRTY_LOG. After enabling KVM_CAP_DIRTY_LOG_RING with an
+acceptable dirty ring size, the virtual machine will switch to the
+dirty ring tracking mode. Further ioctls to either KVM_GET_DIRTY_LOG
+or KVM_CLEAR_DIRTY_LOG will fail.
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 357b3f7b1127..c05b94696b21 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1426,6 +1426,10 @@ int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
unsigned long n;
unsigned long any = 0;
+ /* Dirty ring tracking is exclusive to dirty log tracking */
+ if (kvm->dirty_ring_size)
+ return -EINVAL;
+
*memslot = NULL;
*is_dirty = 0;
@@ -1487,6 +1491,10 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
unsigned long *dirty_bitmap_buffer;
bool flush;
+ /* Dirty ring tracking is exclusive to dirty log tracking */
+ if (kvm->dirty_ring_size)
+ return -EINVAL;
+
as_id = log->slot >> 16;
id = (u16)log->slot;
if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
@@ -1595,6 +1603,10 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
unsigned long *dirty_bitmap_buffer;
bool flush;
+ /* Dirty ring tracking is exclusive to dirty log tracking */
+ if (kvm->dirty_ring_size)
+ return -EINVAL;
+
as_id = log->slot >> 16;
id = (u16)log->slot;
if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
--
2.26.2
next prev parent reply other threads:[~2020-10-23 18:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 18:33 [PATCH v15 00/14] KVM: Dirty ring interface Peter Xu
2020-10-23 18:33 ` [PATCH v15 01/14] KVM: Documentation: Update entry for KVM_X86_SET_MSR_FILTER Peter Xu
2020-10-23 18:33 ` [PATCH v15 02/14] KVM: Documentation: Update entry for KVM_CAP_ENFORCE_PV_CPUID Peter Xu
2020-10-23 18:33 ` [PATCH v15 03/14] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] Peter Xu
2020-10-23 18:33 ` [PATCH v15 04/14] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() Peter Xu
2020-10-23 18:33 ` [PATCH v15 05/14] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2020-10-23 18:33 ` Peter Xu [this message]
2020-10-23 18:33 ` [PATCH v15 07/14] KVM: Don't allocate dirty bitmap if dirty ring is enabled Peter Xu
2020-10-23 18:33 ` [PATCH v15 08/14] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2020-10-23 18:33 ` [PATCH v15 09/14] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2020-10-23 18:33 ` [PATCH v15 10/14] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2020-10-23 18:33 ` [PATCH v15 11/14] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2020-10-23 18:33 ` [PATCH v15 12/14] KVM: selftests: Add dirty ring buffer test Peter Xu
2020-10-23 18:33 ` [PATCH v15 13/14] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2020-10-23 18:33 ` [PATCH v15 14/14] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
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