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kvm: x86, powerpc: do not allow clearing largepages debugfs entry 

The largepages debugfs entry is incremented/decremented as shadow
pages are created or destroyed.  Clearing it will result in an
underflow, which is harmless to KVM but ugly (and could be
misinterpreted by tools that use debugfs information), so make
this particular statistic read-only.

Cc: kvm-ppc@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2019-09-30 18:48:44 +02:00
parent 2e4a75976d
commit 833b45de69
4 changed files with 16 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/powerpc/kvm/book3s.c
View File

@ -36,8 +36,8 @@
#include "book3s.h"
#include "trace.h"
#define VM_STAT(x) offsetof(struct kvm, stat.x), KVM_STAT_VM
#define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU
#define VM_STAT(x, ...) offsetof(struct kvm, stat.x), KVM_STAT_VM, ## __VA_ARGS__
#define VCPU_STAT(x, ...) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU, ## __VA_ARGS__
/* #define EXIT_DEBUG */
@ -69,8 +69,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "pthru_all", VCPU_STAT(pthru_all) },
{ "pthru_host", VCPU_STAT(pthru_host) },
{ "pthru_bad_aff", VCPU_STAT(pthru_bad_aff) },
{ "largepages_2M", VM_STAT(num_2M_pages) },
{ "largepages_1G", VM_STAT(num_1G_pages) },
{ "largepages_2M", VM_STAT(num_2M_pages, .mode = 0444) },
{ "largepages_1G", VM_STAT(num_1G_pages, .mode = 0444) },
{ NULL }
};

6
arch/x86/kvm/x86.c
View File

@ -92,8 +92,8 @@ u64 __read_mostly efer_reserved_bits = ~((u64)(EFER_SCE | EFER_LME | EFER_LMA));
static u64 __read_mostly efer_reserved_bits = ~((u64)EFER_SCE);
#endif
#define VM_STAT(x) offsetof(struct kvm, stat.x), KVM_STAT_VM
#define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU
#define VM_STAT(x, ...) offsetof(struct kvm, stat.x), KVM_STAT_VM, ## __VA_ARGS__
#define VCPU_STAT(x, ...) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU, ## __VA_ARGS__
#define KVM_X2APIC_API_VALID_FLAGS (KVM_X2APIC_API_USE_32BIT_IDS | \
KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK)
@ -212,7 +212,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "mmu_cache_miss", VM_STAT(mmu_cache_miss) },
{ "mmu_unsync", VM_STAT(mmu_unsync) },
{ "remote_tlb_flush", VM_STAT(remote_tlb_flush) },
{ "largepages", VM_STAT(lpages) },
{ "largepages", VM_STAT(lpages, .mode = 0444) },
{ "max_mmu_page_hash_collisions",
VM_STAT(max_mmu_page_hash_collisions) },
{ NULL }

2
include/linux/kvm_host.h
View File

@ -1090,6 +1090,7 @@ enum kvm_stat_kind {
struct kvm_stat_data {
int offset;
int mode;
struct kvm *kvm;
};
@ -1097,6 +1098,7 @@ struct kvm_stats_debugfs_item {
const char *name;
int offset;
enum kvm_stat_kind kind;
int mode;
};
extern struct kvm_stats_debugfs_item debugfs_entries[];
extern struct dentry *kvm_debugfs_dir;

10
virt/kvm/kvm_main.c
View File

@ -617,8 +617,9 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
stat_data->kvm = kvm;
stat_data->offset = p->offset;
stat_data->mode = p->mode ? p->mode : 0644;
kvm->debugfs_stat_data[p - debugfs_entries] = stat_data;
debugfs_create_file(p->name, 0644, kvm->debugfs_dentry,
debugfs_create_file(p->name, stat_data->mode, kvm->debugfs_dentry,
stat_data, stat_fops_per_vm[p->kind]);
}
return 0;
@ -3929,7 +3930,9 @@ static int kvm_debugfs_open(struct inode *inode, struct file *file,
if (!refcount_inc_not_zero(&stat_data->kvm->users_count))
return -ENOENT;
if (simple_attr_open(inode, file, get, set, fmt)) {
if (simple_attr_open(inode, file, get,
stat_data->mode & S_IWUGO ? set : NULL,
fmt)) {
kvm_put_kvm(stat_data->kvm);
return -ENOMEM;
}
@ -4177,7 +4180,8 @@ static void kvm_init_debug(void)
kvm_debugfs_num_entries = 0;
for (p = debugfs_entries; p->name; ++p, kvm_debugfs_num_entries++) {
debugfs_create_file(p->name, 0644, kvm_debugfs_dir,
int mode = p->mode ? p->mode : 0644;
debugfs_create_file(p->name, mode, kvm_debugfs_dir,
(void *)(long)p->offset,
stat_fops[p->kind]);
}