KVM: x86: Encapsulate CPUID entries and metadata in struct

Add a struct to hold the array of CPUID entries and its associated
metadata when handling KVM_GET_SUPPORTED_CPUID.  Lookup and provide
the correct entry in do_host_cpuid(), which eliminates the majority of
array indexing shenanigans, e.g. entries[i -1], and generally makes the
code more readable.  The last array indexing holdout is kvm_get_cpuid(),
which can't really be avoided without throwing the baby out with the
bathwater.

No functional change intended.

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d75d539..59195de 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -287,13 +287,21 @@ static __always_inline void cpuid_mask(u32 *word, int wordnum)
        *word &= boot_cpu_data.x86_capability[wordnum];
 }
 
-static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_entry2 *entry,
-                                             int *nent, int maxnent,
+struct kvm_cpuid_array {
+       struct kvm_cpuid_entry2 *entries;
+       const int maxnent;
+       int nent;
+};
+
+static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
                                              u32 function, u32 index)
 {
-       if (*nent >= maxnent)
+       struct kvm_cpuid_entry2 *entry;
+
+       if (array->nent >= array->maxnent)
                return NULL;
-       ++*nent;
+
+       entry = &array->entries[array->nent++];
 
        entry->function = function;
        entry->index = index;
@@ -325,9 +333,10 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_entry2 *entry,
        return entry;
 }
 
-static int __do_cpuid_func_emulated(struct kvm_cpuid_entry2 *entry,
-                                   u32 func, int *nent, int maxnent)
+static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
 {
+       struct kvm_cpuid_entry2 *entry = &array->entries[array->nent];
+
        entry->function = func;
        entry->index = 0;
        entry->flags = 0;
@@ -335,17 +344,17 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_entry2 *entry,
        switch (func) {
        case 0:
                entry->eax = 7;
-               ++*nent;
+               ++array->nent;
                break;
        case 1:
                entry->ecx = F(MOVBE);
-               ++*nent;
+               ++array->nent;
                break;
        case 7:
                entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
                entry->eax = 0;
                entry->ecx = F(RDPID);
-               ++*nent;
+               ++array->nent;
        default:
                break;
        }
@@ -436,9 +445,9 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
        }
 }
 
-static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
-                                 int *nent, int maxnent)
+static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 {
+       struct kvm_cpuid_entry2 *entry;
        int r, i, max_idx;
        unsigned f_nx = is_efer_nx() ? F(NX) : 0;
 #ifdef CONFIG_X86_64
@@ -514,7 +523,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 
        r = -E2BIG;
 
-       if (WARN_ON(!do_host_cpuid(entry, nent, maxnent, function, 0)))
+       entry = do_host_cpuid(array, function, 0);
+       if (WARN_ON(!entry))
                goto out;
 
        switch (function) {
@@ -539,7 +549,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                entry->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;
 
                for (i = 1, max_idx = entry->eax & 0xff; i < max_idx; ++i) {
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, 0))
+                       entry = do_host_cpuid(array, function, 0);
+                       if (!entry)
                                goto out;
                }
                break;
@@ -550,8 +561,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                 * Read entries until the cache type in the previous entry is
                 * zero, i.e. indicates an invalid entry.
                 */
-               for (i = 1; entry[i - 1].eax & 0x1f; ++i) {
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
+               for (i = 1; entry->eax & 0x1f; ++i) {
+                       entry = do_host_cpuid(array, function, i);
+                       if (!entry)
                                goto out;
                }
                break;
@@ -566,10 +578,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                do_cpuid_7_mask(entry);
 
                for (i = 1, max_idx = entry->eax; i <= max_idx; i++) {
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
+                       entry = do_host_cpuid(array, function, i);
+                       if (!entry)
                                goto out;
 
-                       do_cpuid_7_mask(&entry[i]);
+                       do_cpuid_7_mask(entry);
                }
                break;
        case 9:
@@ -610,15 +623,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
        case 0x1f:
        case 0xb:
                /*
-                * We filled in entry[0] for CPUID(EAX=<function>,
-                * ECX=00H) above.  If its level type (ECX[15:8]) is
-                * zero, then the leaf is unimplemented, and we're
-                * done.  Otherwise, continue to populate entries
-                * until the level type (ECX[15:8]) of the previously
-                * added entry is zero.
+                * Populate entries until the level type (ECX[15:8]) of the
+                * previous entry is zero.  Note, CPUID EAX.{0x1f,0xb}.0 is
+                * the starting entry, filled by the primary do_host_cpuid().
                 */
-               for (i = 1; entry[i - 1].ecx & 0xff00; ++i) {
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
+               for (i = 1; entry->ecx & 0xff00; ++i) {
+                       entry = do_host_cpuid(array, function, i);
+                       if (!entry)
                                goto out;
                }
                break;
@@ -633,24 +644,26 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                if (!supported)
                        break;
 
-               if (!do_host_cpuid(&entry[1], nent, maxnent, function, 1))
+               entry = do_host_cpuid(array, function, 1);
+               if (!entry)
                        goto out;
 
-               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)))
-                       entry[1].ebx = xstate_required_size(supported, true);
+               entry->eax &= kvm_cpuid_D_1_eax_x86_features;
+               cpuid_mask(&entry->eax, CPUID_D_1_EAX);
+               if (entry->eax & (F(XSAVES)|F(XSAVEC)))
+                       entry->ebx = xstate_required_size(supported, true);
                else
-                       entry[1].ebx = 0;
+                       entry->ebx = 0;
                /* Saving XSS controlled state via XSAVES isn't supported. */
-               entry[1].ecx = 0;
-               entry[1].edx = 0;
+               entry->ecx = 0;
+               entry->edx = 0;
 
-               for (idx = 2, i = 2; idx < 64; ++idx) {
+               for (idx = 2; idx < 64; ++idx) {
                        if (!(supported & BIT_ULL(idx)))
                                continue;
 
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, idx))
+                       entry = do_host_cpuid(array, function, idx);
+                       if (!entry)
                                goto out;
 
                        /*
@@ -660,14 +673,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                         * reach this point, and they should have a non-zero
                         * save state size.
                         */
-                       if (WARN_ON_ONCE(!entry[i].eax || (entry[i].ecx & 1))) {
-                               --*nent;
+                       if (WARN_ON_ONCE(!entry->eax || (entry->ecx & 1))) {
+                               --array->nent;
                                continue;
                        }
 
-                       entry[i].ecx = 0;
-                       entry[i].edx = 0;
-                       ++i;
+                       entry->ecx = 0;
+                       entry->edx = 0;
                }
                break;
        }
@@ -677,7 +689,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
                        break;
 
                for (i = 1, max_idx = entry->eax; i <= max_idx; ++i) {
-                       if (!do_host_cpuid(&entry[i], nent, maxnent, function, i))
+                       if (!do_host_cpuid(array, function, i))
                                goto out;
                }
                break;
@@ -802,22 +814,22 @@ out:
        return r;
 }
 
-static int do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 func,
-                        int *nent, int maxnent, unsigned int type)
+static int do_cpuid_func(struct kvm_cpuid_array *array, u32 func,
+                        unsigned int type)
 {
-       if (*nent >= maxnent)
+       if (array->nent >= array->maxnent)
                return -E2BIG;
 
        if (type == KVM_GET_EMULATED_CPUID)
-               return __do_cpuid_func_emulated(entry, func, nent, maxnent);
+               return __do_cpuid_func_emulated(array, func);
 
-       return __do_cpuid_func(entry, func, nent, maxnent);
+       return __do_cpuid_func(array, func);
 }
 
 #define CENTAUR_CPUID_SIGNATURE 0xC0000000
 
-static int get_cpuid_func(struct kvm_cpuid_entry2 *entries, u32 func,
-                         int *nent, int maxnent, unsigned int type)
+static int get_cpuid_func(struct kvm_cpuid_array *array, u32 func,
+                         unsigned int type)
 {
        u32 limit;
        int r;
@@ -826,16 +838,16 @@ static int get_cpuid_func(struct kvm_cpuid_entry2 *entries, u32 func,
            boot_cpu_data.x86_vendor != X86_VENDOR_CENTAUR)
                return 0;
 
-       r = do_cpuid_func(&entries[*nent], func, nent, maxnent, type);
+       r = do_cpuid_func(array, func, type);
        if (r)
                return r;
 
-       limit = entries[*nent - 1].eax;
+       limit = array->entries[array->nent - 1].eax;
        for (func = func + 1; func <= limit; ++func) {
-               if (*nent >= maxnent)
+               if (array->nent >= array->maxnent)
                        return -E2BIG;
 
-               r = do_cpuid_func(&entries[*nent], func, nent, maxnent, type);
+               r = do_cpuid_func(array, func, type);
                if (r)
                        break;
        }
@@ -878,8 +890,11 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
                0, 0x80000000, CENTAUR_CPUID_SIGNATURE, KVM_CPUID_SIGNATURE,
        };
 
-       struct kvm_cpuid_entry2 *cpuid_entries;
-       int nent = 0, r, i;
+       struct kvm_cpuid_array array = {
+               .nent = 0,
+               .maxnent = cpuid->nent,
+       };
+       int r, i;
 
        if (cpuid->nent < 1)
                return -E2BIG;
@@ -889,25 +904,24 @@ int kvm_dev_ioctl_get_cpuid(struct kvm_cpuid2 *cpuid,
        if (sanity_check_entries(entries, cpuid->nent, type))
                return -EINVAL;
 
-       cpuid_entries = vzalloc(array_size(sizeof(struct kvm_cpuid_entry2),
+       array.entries = vzalloc(array_size(sizeof(struct kvm_cpuid_entry2),
                                           cpuid->nent));
-       if (!cpuid_entries)
+       if (!array.entries)
                return -ENOMEM;
 
        for (i = 0; i < ARRAY_SIZE(funcs); i++) {
-               r = get_cpuid_func(cpuid_entries, funcs[i], &nent, cpuid->nent,
-                                  type);
+               r = get_cpuid_func(&array, funcs[i], type);
                if (r)
                        goto out_free;
        }
-       cpuid->nent = nent;
+       cpuid->nent = array.nent;
 
-       if (copy_to_user(entries, cpuid_entries,
-                        nent * sizeof(struct kvm_cpuid_entry2)))
+       if (copy_to_user(entries, array.entries,
+                        array.nent * sizeof(struct kvm_cpuid_entry2)))
                r = -EFAULT;
 
 out_free:
-       vfree(cpuid_entries);
+       vfree(array.entries);
        return r;
 }