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KVM: Refactor and simplify kvm_dev_ioctl_get_supported_cpuid
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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>
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Sasha Levin authored and Avi Kivity committed Dec 27, 2011
1 parent fb21536 commit 831bf66
Showing 1 changed file with 63 additions and 50 deletions.
113 changes: 63 additions & 50 deletions arch/x86/kvm/cpuid.c
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Original file line number Diff line number Diff line change
Expand Up @@ -183,9 +183,10 @@ static bool supported_xcr0_bit(unsigned bit)

#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)
Expand Down Expand Up @@ -246,6 +247,12 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

/* 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;

Expand All @@ -271,7 +278,10 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

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;
Expand All @@ -284,7 +294,10 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

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;
Expand Down Expand Up @@ -316,7 +329,10 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

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;
Expand All @@ -331,7 +347,10 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
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;
Expand Down Expand Up @@ -416,17 +435,41 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

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;
Expand All @@ -437,61 +480,31 @@ int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
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;

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);


r = 0;
for (i = 0; i < ARRAY_SIZE(param); i++) {
struct kvm_cpuid_param *ent = &param[i];

r = -E2BIG;
if (nent >= cpuid->nent)
goto out_free;
if (ent->qualifier && !ent->qualifier(ent))
continue;

/* 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)))
Expand Down

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