| Message ID | 20210730220455.26054-2-peterx@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: X86: Some light optimizations on rmap logic | expand |
On Fri, Jul 30, 2021 at 06:04:49PM -0400, Peter Xu wrote: > Allow archs to create arch-specific nodes under kvm->debugfs_dentry directory > besides the stats fields. The new interface kvm_arch_create_vm_debugfs() is > defined but not yet used. It's called after kvm->debugfs_dentry is created, so > it can be referenced directly in kvm_arch_create_vm_debugfs(). Arch should > define their own versions when they want to create extra debugfs nodes. > > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > include/linux/kvm_host.h | 1 + > virt/kvm/kvm_main.c | 20 +++++++++++++++++++- > 2 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 9d6b4ad407b8..a3ec3271c4c8 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -1067,6 +1067,7 @@ bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu); > bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu); > int kvm_arch_post_init_vm(struct kvm *kvm); > void kvm_arch_pre_destroy_vm(struct kvm *kvm); > +int kvm_arch_create_vm_debugfs(struct kvm *kvm); > > #ifndef __KVM_HAVE_ARCH_VM_ALLOC > /* > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index a96cbe24c688..327f8fae80a5 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -915,7 +915,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) > char dir_name[ITOA_MAX_LEN * 2]; > struct kvm_stat_data *stat_data; > const struct _kvm_stats_desc *pdesc; > - int i; > + int i, ret; > int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc + > kvm_vcpu_stats_header.num_desc; > > @@ -960,6 +960,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) > kvm->debugfs_dentry, stat_data, > &stat_fops_per_vm); > } > + > + ret = kvm_arch_create_vm_debugfs(kvm); > + if (ret) { > + kvm_destroy_vm_debugfs(kvm); > + return i; > + } > + > return 0; > } > > @@ -980,6 +987,17 @@ void __weak kvm_arch_pre_destroy_vm(struct kvm *kvm) > { > } > > +/* > + * Called after per-vm debugfs created. When called kvm->debugfs_dentry should > + * be setup already, so we can create arch-specific debugfs entries under it. > + * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so > + * a per-arch destroy interface is not needed. > + */ > +int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) This should be a void function, nothing should matter if creating debugfs files succeeds or not. As proof, your one implementation always returned 0 :) thanks, greg k-h
On Tue, Aug 03, 2021 at 01:15:19PM +0200, Greg KH wrote: > > +/* > > + * Called after per-vm debugfs created. When called kvm->debugfs_dentry should > > + * be setup already, so we can create arch-specific debugfs entries under it. > > + * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so > > + * a per-arch destroy interface is not needed. > > + */ > > +int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) > > This should be a void function, nothing should matter if creating > debugfs files succeeds or not. > > As proof, your one implementation always returned 0 :) Right. :) But we do have code that prepares for a failure on debugfs creations, please have a look at kvm_create_vm_debugfs(). So I kept that for per-arch hook. The existing x86 one should not fail, but it's a hope that we can convert some other arch's existing debugfs code into per-arch hook like what we did with x86 here. I didn't check again (please refer to the cover letter; we do have some of those), but it's still easier to still allow per-arch hook to fail the vm creation just like what we have for kvm_create_vm_debugfs(). PS: It makes sense to me to fail vm creation if 99% of those debugfs creation failures are about -ENOMEM; e.g. early failure sounds better than failing right after VM booted. Meanwhile, I never expected to receive comments from you; thanks for having a look!
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9d6b4ad407b8..a3ec3271c4c8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1067,6 +1067,7 @@ bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu); bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu); int kvm_arch_post_init_vm(struct kvm *kvm); void kvm_arch_pre_destroy_vm(struct kvm *kvm); +int kvm_arch_create_vm_debugfs(struct kvm *kvm); #ifndef __KVM_HAVE_ARCH_VM_ALLOC /* diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a96cbe24c688..327f8fae80a5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -915,7 +915,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) char dir_name[ITOA_MAX_LEN * 2]; struct kvm_stat_data *stat_data; const struct _kvm_stats_desc *pdesc; - int i; + int i, ret; int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc + kvm_vcpu_stats_header.num_desc; @@ -960,6 +960,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd) kvm->debugfs_dentry, stat_data, &stat_fops_per_vm); } + + ret = kvm_arch_create_vm_debugfs(kvm); + if (ret) { + kvm_destroy_vm_debugfs(kvm); + return i; + } + return 0; } @@ -980,6 +987,17 @@ void __weak kvm_arch_pre_destroy_vm(struct kvm *kvm) { } +/* + * Called after per-vm debugfs created. When called kvm->debugfs_dentry should + * be setup already, so we can create arch-specific debugfs entries under it. + * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so + * a per-arch destroy interface is not needed. + */ +int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm) +{ + return 0; +} + static struct kvm *kvm_create_vm(unsigned long type) { struct kvm *kvm = kvm_arch_alloc_vm();
Allow archs to create arch-specific nodes under kvm->debugfs_dentry directory besides the stats fields. The new interface kvm_arch_create_vm_debugfs() is defined but not yet used. It's called after kvm->debugfs_dentry is created, so it can be referenced directly in kvm_arch_create_vm_debugfs(). Arch should define their own versions when they want to create extra debugfs nodes. Signed-off-by: Peter Xu <peterx@redhat.com> --- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 20 +++++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-)