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authorPeter Xu <peterx@redhat.com>2019-05-08 17:15:47 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-05-08 13:48:24 +0200
commitd7547c55cbe7471255ca51f14bcd4699f5eaabe5 (patch)
tree1d616aada1dec45414a38ed39f4017223ddccea8
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>
-rw-r--r--Documentation/virtual/kvm/api.txt15
-rw-r--r--include/uapi/linux/kvm.h5
-rw-r--r--tools/testing/selftests/kvm/dirty_log_test.c4
-rw-r--r--virt/kvm/kvm_main.c4
4 files changed, 17 insertions, 11 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.
----------------------
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 6d4ea4b6c922..d673734c46cb 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -986,8 +986,9 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_HYPERV_ENLIGHTENED_VMCS 163
#define KVM_CAP_EXCEPTION_PAYLOAD 164
#define KVM_CAP_ARM_VM_IPA_SIZE 165
-#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
+#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166 /* Obsolete */
#define KVM_CAP_HYPERV_CPUID 167
+#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 168
#ifdef KVM_CAP_IRQ_ROUTING
@@ -1434,7 +1435,7 @@ struct kvm_enc_region {
#define KVM_GET_NESTED_STATE _IOWR(KVMIO, 0xbe, struct kvm_nested_state)
#define KVM_SET_NESTED_STATE _IOW(KVMIO, 0xbf, struct kvm_nested_state)
-/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT */
+/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT_2 */
#define KVM_CLEAR_DIRTY_LOG _IOWR(KVMIO, 0xc0, struct kvm_clear_dirty_log)
/* Available with KVM_CAP_HYPERV_CPUID */
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index 052fb5856df4..a29d1119ccb3 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -311,7 +311,7 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
#ifdef USE_CLEAR_DIRTY_LOG
struct kvm_enable_cap cap = {};
- cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT;
+ cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2;
cap.args[0] = 1;
vm_enable_cap(vm, &cap);
#endif
@@ -427,7 +427,7 @@ int main(int argc, char *argv[])
int opt, i;
#ifdef USE_CLEAR_DIRTY_LOG
- if (!kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT)) {
+ if (!kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2)) {
fprintf(stderr, "KVM_CLEAR_DIRTY_LOG not available, skipping tests\n");
exit(KSFT_SKIP);
}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7883e0ad07fe..f4e02cd8fa43 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3110,7 +3110,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
case KVM_CAP_CHECK_EXTENSION_VM:
case KVM_CAP_ENABLE_CAP_VM:
#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
- case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT:
+ case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2:
#endif
return 1;
#ifdef CONFIG_KVM_MMIO
@@ -3148,7 +3148,7 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
{
switch (cap->cap) {
#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
- case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT:
+ case KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2:
if (cap->flags || (cap->args[0] & ~1))
return -EINVAL;
kvm->manual_dirty_log_protect = cap->args[0];