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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id a16sm4351438wrx.87.2020.02.21.06.58.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Feb 2020 06:58:48 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 16/61] KVM: x86: Encapsulate CPUID entries and metadata in struct In-Reply-To: <20200201185218.24473-17-sean.j.christopherson@intel.com> References: <20200201185218.24473-1-sean.j.christopherson@intel.com> <20200201185218.24473-17-sean.j.christopherson@intel.com> Date: Fri, 21 Feb 2020 15:58:47 +0100 Message-ID: <87y2swq95k.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > 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 > --- > 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); I'd change this to entry = do_host_cpuid(array, function, 0); to match other call sites. > + 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); Would it make sense to move 'if (array->nent >= array->maxnent)' check to __do_cpuid_func_emulated() to match do_host_cpuid()? > > - 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); do_cpuid_func() above is already doing 'if (array->nent >= array->maxnent)' check and returns -E2BIG when it fails, maybe the same check here in get_cpuid_func() is not needed? > 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; > } Reviewed-by: Vitaly Kuznetsov -- Vitaly