KVM: Refactor and simplify kvm_dev_ioctl_get_supported_cpuid
This patch cleans and simplifies kvm_dev_ioctl_get_supported_cpuid by using a table
instead of duplicating code as Avi suggested.
This patch also fixes a bug where kvm_dev_ioctl_get_supported_cpuid would return
-E2BIG when amount of entries passed was just right.
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 47be763..52593e8 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -183,9 +183,10 @@
#define F(x) bit(X86_FEATURE_##x)
-static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
+static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
u32 index, int *nent, int maxnent)
{
+ int r;
unsigned f_nx = is_efer_nx() ? F(NX) : 0;
#ifdef CONFIG_X86_64
unsigned f_gbpages = (kvm_x86_ops->get_lpage_level() == PT_PDPE_LEVEL)
@@ -246,6 +247,12 @@
/* all calls to cpuid_count() should be made on the same cpu */
get_cpu();
+
+ r = -E2BIG;
+
+ if (*nent >= maxnent)
+ goto out;
+
do_cpuid_1_ent(entry, function, index);
++*nent;
@@ -271,7 +278,10 @@
entry->flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
- for (t = 1; t < times && *nent < maxnent; ++t) {
+ for (t = 1; t < times; ++t) {
+ if (*nent >= maxnent)
+ goto out;
+
do_cpuid_1_ent(&entry[t], function, 0);
entry[t].flags |= KVM_CPUID_FLAG_STATEFUL_FUNC;
++*nent;
@@ -284,7 +294,10 @@
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
/* read more entries until cache_type is zero */
- for (i = 1; *nent < maxnent; ++i) {
+ for (i = 1; ; ++i) {
+ if (*nent >= maxnent)
+ goto out;
+
cache_type = entry[i - 1].eax & 0x1f;
if (!cache_type)
break;
@@ -316,7 +329,10 @@
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
/* read more entries until level_type is zero */
- for (i = 1; *nent < maxnent; ++i) {
+ for (i = 1; ; ++i) {
+ if (*nent >= maxnent)
+ goto out;
+
level_type = entry[i - 1].ecx & 0xff00;
if (!level_type)
break;
@@ -331,7 +347,10 @@
int idx, i;
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
- for (idx = 1, i = 1; *nent < maxnent && idx < 64; ++idx) {
+ for (idx = 1, i = 1; idx < 64; ++idx) {
+ if (*nent >= maxnent)
+ goto out;
+
do_cpuid_1_ent(&entry[i], function, idx);
if (entry[i].eax == 0 || !supported_xcr0_bit(idx))
continue;
@@ -416,17 +435,41 @@
kvm_x86_ops->set_supported_cpuid(function, entry);
+ r = 0;
+
+out:
put_cpu();
+
+ return r;
}
#undef F
+struct kvm_cpuid_param {
+ u32 func;
+ u32 idx;
+ bool has_leaf_count;
+ bool (*qualifier)(struct kvm_cpuid_param *param);
+};
+
+static bool is_centaur_cpu(struct kvm_cpuid_param *param)
+{
+ return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
+}
+
int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries)
{
struct kvm_cpuid_entry2 *cpuid_entries;
- int limit, nent = 0, r = -E2BIG;
+ int limit, nent = 0, r = -E2BIG, i;
u32 func;
+ static struct kvm_cpuid_param param[] = {
+ { .func = 0, .has_leaf_count = true },
+ { .func = 0x80000000, .has_leaf_count = true },
+ { .func = 0xC0000000, .qualifier = is_centaur_cpu, .has_leaf_count = true },
+ { .func = KVM_CPUID_SIGNATURE },
+ { .func = KVM_CPUID_FEATURES },
+ };
if (cpuid->nent < 1)
goto out;
@@ -437,61 +480,31 @@
if (!cpuid_entries)
goto out;
- do_cpuid_ent(&cpuid_entries[0], 0, 0, &nent, cpuid->nent);
- limit = cpuid_entries[0].eax;
- for (func = 1; func <= limit && nent < cpuid->nent; ++func)
- do_cpuid_ent(&cpuid_entries[nent], func, 0,
- &nent, cpuid->nent);
- r = -E2BIG;
- if (nent >= cpuid->nent)
- goto out_free;
+ r = 0;
+ for (i = 0; i < ARRAY_SIZE(param); i++) {
+ struct kvm_cpuid_param *ent = ¶m[i];
- do_cpuid_ent(&cpuid_entries[nent], 0x80000000, 0, &nent, cpuid->nent);
- limit = cpuid_entries[nent - 1].eax;
- for (func = 0x80000001; func <= limit && nent < cpuid->nent; ++func)
- do_cpuid_ent(&cpuid_entries[nent], func, 0,
- &nent, cpuid->nent);
+ if (ent->qualifier && !ent->qualifier(ent))
+ continue;
-
-
- r = -E2BIG;
- if (nent >= cpuid->nent)
- goto out_free;
-
- /* Add support for Centaur's CPUID instruction. */
- if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR) {
- do_cpuid_ent(&cpuid_entries[nent], 0xC0000000, 0,
+ r = do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
&nent, cpuid->nent);
- r = -E2BIG;
- if (nent >= cpuid->nent)
+ if (r)
goto out_free;
+ if (!ent->has_leaf_count)
+ continue;
+
limit = cpuid_entries[nent - 1].eax;
- for (func = 0xC0000001;
- func <= limit && nent < cpuid->nent; ++func)
- do_cpuid_ent(&cpuid_entries[nent], func, 0,
- &nent, cpuid->nent);
+ for (func = ent->func + 1; func <= limit && nent < cpuid->nent && r == 0; ++func)
+ r = do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
+ &nent, cpuid->nent);
- r = -E2BIG;
- if (nent >= cpuid->nent)
+ if (r)
goto out_free;
}
- do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_SIGNATURE, 0, &nent,
- cpuid->nent);
-
- r = -E2BIG;
- if (nent >= cpuid->nent)
- goto out_free;
-
- do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_FEATURES, 0, &nent,
- cpuid->nent);
-
- r = -E2BIG;
- if (nent >= cpuid->nent)
- goto out_free;
-
r = -EFAULT;
if (copy_to_user(entries, cpuid_entries,
nent * sizeof(struct kvm_cpuid_entry2)))