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authorPeter Xu2019-05-08 17:15:47 +0800
committerPaolo Bonzini2019-05-08 13:48:24 +0200
commitd7547c55cbe7471255ca51f14bcd4699f5eaabe5 (patch)
tree1d616aada1dec45414a38ed39f4017223ddccea8 /Documentation/virtual/kvm
parent53eac7a8f8cf3d7dc5ecac1946f31442f5eee5f3 (diff)
KVM: Introduce KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
The previous KVM_CAP_MANUAL_DIRTY_LOG_PROTECT has some problem which blocks the correct usage from userspace. Obsolete the old one and introduce a new capability bit for it. Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual/kvm')
-rw-r--r--Documentation/virtual/kvm/api.txt15
1 files changed, 10 insertions, 5 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 675cb0bea903..47a5eb00bc53 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -330,7 +330,7 @@ They must be less than the value that KVM_CHECK_EXTENSION returns for
the KVM_CAP_MULTI_ADDRESS_SPACE capability.
The bits in the dirty bitmap are cleared before the ioctl returns, unless
-KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is enabled. For more information,
+KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is enabled. For more information,
see the description of the capability.
4.9 KVM_SET_MEMORY_ALIAS
@@ -3791,7 +3791,7 @@ to I/O ports.
4.117 KVM_CLEAR_DIRTY_LOG (vm ioctl)
-Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT
+Capability: KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
Architectures: x86
Type: vm ioctl
Parameters: struct kvm_dirty_log (in)
@@ -3824,10 +3824,10 @@ the address space for which you want to return the dirty bitmap.
They must be less than the value that KVM_CHECK_EXTENSION returns for
the KVM_CAP_MULTI_ADDRESS_SPACE capability.
-This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT
+This ioctl is mostly useful when KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
is enabled; for more information, see the description of the capability.
However, it can always be used as long as KVM_CHECK_EXTENSION confirms
-that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is present.
+that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present.
4.118 KVM_GET_SUPPORTED_HV_CPUID
@@ -4780,7 +4780,7 @@ and injected exceptions.
* For the new DR6 bits, note that bit 16 is set iff the #DB exception
will clear DR6.RTM.
-7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT
+7.18 KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2
Architectures: all
Parameters: args[0] whether feature should be enabled or not
@@ -4803,6 +4803,11 @@ while userspace can see false reports of dirty pages. Manual reprotection
helps reducing this time, improving guest performance and reducing the
number of dirty log false positives.
+KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name
+KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make
+it hard or impossible to use it correctly. The availability of
+KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 signals that those bugs are fixed.
+Userspace should not try to use KVM_CAP_MANUAL_DIRTY_LOG_PROTECT.
8. Other capabilities.
----------------------