From e53c95e8d41ef9927d1d5ff031db1fd6989ec16b Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 2 Mar 2020 15:56:19 -0800 Subject: [PATCH] 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 Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- 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..59195de22d8f 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, 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=, - * 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; } -- GitLab