kvm: x86: Add memcg accounting to KVM allocations

There are many KVM kernel memory allocations which are tied to the life of
the VM process and should be charged to the VM process's cgroup. If the
allocations aren't tied to the process, the OOM killer will not know
that killing the process will free the associated kernel memory.
Add __GFP_ACCOUNT flags to many of the allocations which are not yet being
charged to the VM process's cgroup.

Tested:
	Ran all kvm-unit-tests on a 64 bit Haswell machine, the patch
	introduced no new failures.
	Ran a kernel memory accounting test which creates a VM to touch
	memory and then checks that the kernel memory allocated for the
	process is within certain bounds.
	With this patch we account for much more of the vmalloc and slab memory
	allocated for the VM.

There remain a few allocations which should be charged to the VM's
cgroup but are not. In x86, they include:
	vcpu->arch.pio_data
There allocations are unaccounted in this patch because they are mapped
to userspace, and accounting them to a cgroup causes problems. This
should be addressed in a future patch.

Signed-off-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 96f87d356c79..3de586f89730 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3879,7 +3879,8 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		r = -EINVAL;
 		if (!lapic_in_kernel(vcpu))
 			goto out;
-		u.lapic = kzalloc(sizeof(struct kvm_lapic_state), GFP_KERNEL);
+		u.lapic = kzalloc(sizeof(struct kvm_lapic_state),
+				GFP_KERNEL_ACCOUNT);
 
 		r = -ENOMEM;
 		if (!u.lapic)
@@ -4066,7 +4067,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		break;
 	}
 	case KVM_GET_XSAVE: {
-		u.xsave = kzalloc(sizeof(struct kvm_xsave), GFP_KERNEL);
+		u.xsave = kzalloc(sizeof(struct kvm_xsave), GFP_KERNEL_ACCOUNT);
 		r = -ENOMEM;
 		if (!u.xsave)
 			break;
@@ -4090,7 +4091,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		break;
 	}
 	case KVM_GET_XCRS: {
-		u.xcrs = kzalloc(sizeof(struct kvm_xcrs), GFP_KERNEL);
+		u.xcrs = kzalloc(sizeof(struct kvm_xcrs), GFP_KERNEL_ACCOUNT);
 		r = -ENOMEM;
 		if (!u.xcrs)
 			break;
@@ -9040,14 +9041,15 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 		static_key_slow_inc(&kvm_no_apic_vcpu);
 
 	vcpu->arch.mce_banks = kzalloc(KVM_MAX_MCE_BANKS * sizeof(u64) * 4,
-				       GFP_KERNEL);
+				       GFP_KERNEL_ACCOUNT);
 	if (!vcpu->arch.mce_banks) {
 		r = -ENOMEM;
 		goto fail_free_lapic;
 	}
 	vcpu->arch.mcg_cap = KVM_MAX_MCE_BANKS;
 
-	if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask, GFP_KERNEL)) {
+	if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask,
+				GFP_KERNEL_ACCOUNT)) {
 		r = -ENOMEM;
 		goto fail_free_mce_banks;
 	}
@@ -9306,13 +9308,13 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 		slot->arch.rmap[i] =
 			kvcalloc(lpages, sizeof(*slot->arch.rmap[i]),
-				 GFP_KERNEL);
+				 GFP_KERNEL_ACCOUNT);
 		if (!slot->arch.rmap[i])
 			goto out_free;
 		if (i == 0)
 			continue;
 
-		linfo = kvcalloc(lpages, sizeof(*linfo), GFP_KERNEL);
+		linfo = kvcalloc(lpages, sizeof(*linfo), GFP_KERNEL_ACCOUNT);
 		if (!linfo)
 			goto out_free;