[PATCH v2 13/66] KVM: x86: Consolidate CPUID array max num entries checking

Sean Christopherson
2020-03-03T00:01:48Z

Move the nent vs. maxnent check and nent increment into do_host_cpuid()
to consolidate what is now identical code. To signal success vs.
failure, return the entry and NULL respectively. A future patch will
build on this to also move the entry retrieval into do_host_cpuid().

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/kvm/cpuid.c | 49 +++++++++++++++-----------------------------
1 file changed, 17 insertions(+), 32 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 52f0af4e10d5..1ae3b2502333 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -287,9 +287,14 @@ static __always_inline void cpuid_mask(u32 *word, int wordnum)
*word &= boot_cpu_data.x86_capability[wordnum];
}

-static void do_host_cpuid(struct kvm_cpuid_entry2 *entry, u32 function,
- u32 index)
+static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_entry2 *entry,
+ int *nent, int maxnent,
+ u32 function, u32 index)
{
+ if (*nent >= maxnent)
+ return NULL;
+ ++*nent;
+
entry->function = function;
entry->index = index;
entry->flags = 0;
@@ -316,6 +321,8 @@ static void do_host_cpuid(struct kvm_cpuid_entry2 *entry, u32 function,
entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
break;
}
+
+ return entry;
}

static int __do_cpuid_func_emulated(struct kvm_cpuid_entry2 *entry,
@@ -507,12 +514,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,

r = -E2BIG;

- if (WARN_ON(*nent >= maxnent))
+ if (WARN_ON(!do_host_cpuid(entry, nent, maxnent, function, 0)))
goto out;

- do_host_cpuid(entry, function, 0);
- ++*nent;
-
switch (function) {
case 0:
/* Limited to the highest leaf implemented in KVM. */
@@ -536,11 +540,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,

entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
for (t = 1; t < times; ++t) {
- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[t], nent, maxnent, function, 0))
goto out;
-
- do_host_cpuid(&entry[t], function, 0);
- ++*nent;
}
break;
}
@@ -555,10 +556,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
if (!cache_type)
break;

- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
goto out;
- do_host_cpuid(&entry[i], function, i);
- ++*nent;
}
break;
}
@@ -575,12 +574,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
do_cpuid_7_mask(entry);

for (i = 1; i <= entry->eax; i++) {
- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
goto out;

- do_host_cpuid(&entry[i], function, i);
- ++*nent;
-
do_cpuid_7_mask(&entry[i]);
}
break;
@@ -633,11 +629,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
* added entry is zero.
*/
for (i = 1; entry[i - 1].ecx & 0xff00; ++i) {
- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
goto out;
-
- do_host_cpuid(&entry[i], function, i);
- ++*nent;
}
break;
}
@@ -652,12 +645,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
if (!supported)
break;

- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[1], nent, maxnent, function, 1))
goto out;

- do_host_cpuid(&entry[1], function, 1);
- ++*nent;
-
entry[1].eax &= kvm_cpuid_D_1_eax_x86_features;
cpuid_mask(&entry[1].eax, CPUID_D_1_EAX);
if (entry[1].eax & (F(XSAVES)|F(XSAVEC)))
@@ -672,12 +662,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
if (!(supported & BIT_ULL(idx)))
continue;

- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[i], nent, maxnent, function, idx))
goto out;

- do_host_cpuid(&entry[i], function, idx);
- ++*nent;
-
/*
* The @supported check above should have filtered out
* invalid sub-leafs as well as sub-leafs managed by
@@ -704,10 +691,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
break;

for (t = 1; t <= times; ++t) {
- if (*nent >= maxnent)
+ if (!do_host_cpuid(&entry[t], nent, maxnent, function, t))
goto out;
- do_host_cpuid(&entry[t], function, t);
- ++*nent;
}
break;
}
--
2.24.1