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Commit d7547c55 authored by Peter Xu's avatar Peter Xu Committed by Paolo Bonzini
Browse files

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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 53eac7a8

Documentation/virtual/kvm/api.txt

+10 −5
Original line number Diff line number Diff line
@@ -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.

----------------------

include/uapi/linux/kvm.h

+3 −2
Original line number Diff line number Diff line
@@ -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 */

tools/testing/selftests/kvm/dirty_log_test.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

	}

virt/kvm/kvm_main.c

+2 −2
Original line number Diff line number Diff line
@@ -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];