lkml.org 
[lkml]   [2020]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 16/61] KVM: x86: Encapsulate CPUID entries and metadata in struct
    Date
    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.

    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    ---
    arch/x86/kvm/cpuid.c | 138 ++++++++++++++++++++++++-------------------
    1 file changed, 76 insertions(+), 62 deletions(-)

    diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    index d75d539da759..f9cfc69199f0 100644
    --- 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, 2, 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 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
    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;
    }

    --
    2.24.1
    \
     
     \ /
      Last update: 2020-02-01 19:54    [W:4.239 / U:0.332 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site