On 11/25/2011 10:12 AM, Sasha Levin wrote:
> This patch cleans and simplifies kvm_dev_ioctl_get_supported_cpuid by using a table
> instead of duplicating code as Avi suggested.
>
> This patch also fixes a bug where kvm_dev_ioctl_get_supported_cpuid would return
> -E2BIG when amount of entries passed was just right.
>
> Cc: Avi Kivity <avi@xxxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> ---
> arch/x86/kvm/cpuid.c | 78 ++++++++++++++++++++++---------------------------
> 1 files changed, 35 insertions(+), 43 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index bbaa6d8..c9ede4d 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -425,12 +425,31 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
>
> #undef F
>
> +struct kvm_cpuid_param {
> + u32 func;
> + u32 idx;
> + u32 leaves;
What does 'leaves' mean? That it has a leaf count in eax? if so it
want a better name and to be a bool.
> + int (*qualifier)(struct kvm_cpuid_param *param);
bool
> +};
> +
> +int is_centaur_cpu(struct kvm_cpuid_param *param)
> +{
> + return boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR;
> +}
> +
static
> int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
> struct kvm_cpuid_entry2 __user *entries)
> {
> struct kvm_cpuid_entry2 *cpuid_entries;
> - int limit, nent = 0, r = -E2BIG;
> + int limit, nent = 0, r = -E2BIG, i;
> u32 func;
> + struct kvm_cpuid_param param[] = {
> + { .func = 0, .leaves = 1 },
> + { .func = 0x80000000, .leaves = 1 },
> + { .func = 0xC0000000, .qualifier = is_centaur_cpu, .leaves = 1 },
> + { .func = KVM_CPUID_SIGNATURE },
> + { .func = KVM_CPUID_FEATURES },
> + };
static
>
> if (cpuid->nent < 1)
> goto out;
> @@ -441,59 +460,32 @@ int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
> if (!cpuid_entries)
> goto out;
>
> - do_cpuid_ent(&cpuid_entries[0], 0, 0, &nent, cpuid->nent);
> - limit = cpuid_entries[0].eax;
> - for (func = 1; func <= limit && nent < cpuid->nent; ++func)
> - do_cpuid_ent(&cpuid_entries[nent], func, 0,
> - &nent, cpuid->nent);
> - r = -E2BIG;
> - if (nent >= cpuid->nent)
> - goto out_free;
> -
> - do_cpuid_ent(&cpuid_entries[nent], 0x80000000, 0, &nent, cpuid->nent);
> - limit = cpuid_entries[nent - 1].eax;
> - for (func = 0x80000001; func <= limit && nent < cpuid->nent; ++func)
> - do_cpuid_ent(&cpuid_entries[nent], func, 0,
> - &nent, cpuid->nent);
> -
> + for (i = 0; i < ARRAY_SIZE(param); i++) {
> + struct kvm_cpuid_param *ent = ¶m[i];
>
> + if (ent->qualifier && !ent->qualifier(ent))
> + continue;
>
> - r = -E2BIG;
> - if (nent >= cpuid->nent)
> - goto out_free;
> + if (nent >= cpuid->nent)
> + break;
>
> - /* Add support for Centaur's CPUID instruction. */
> - if (boot_cpu_data.x86_vendor == X86_VENDOR_CENTAUR) {
> - do_cpuid_ent(&cpuid_entries[nent], 0xC0000000, 0,
> + do_cpuid_ent(&cpuid_entries[nent], ent->func, ent->idx,
> &nent, cpuid->nent);
>
> - r = -E2BIG;
> - if (nent >= cpuid->nent)
> - goto out_free;
> + if (!ent->leaves)
> + continue;
>
> limit = cpuid_entries[nent - 1].eax;
> - for (func = 0xC0000001;
> - func <= limit && nent < cpuid->nent; ++func)
> - do_cpuid_ent(&cpuid_entries[nent], func, 0,
> - &nent, cpuid->nent);
> + for (func = ent->func + 1; func <= limit && nent < cpuid->nent; ++func)
> + do_cpuid_ent(&cpuid_entries[nent], func, ent->idx,
> + &nent, cpuid->nent);
>
> - r = -E2BIG;
> - if (nent >= cpuid->nent)
> - goto out_free;
> + if (func <= limit)
> + break;
> }
>
> - do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_SIGNATURE, 0, &nent,
> - cpuid->nent);
> -
> - r = -E2BIG;
> - if (nent >= cpuid->nent)
> - goto out_free;
> -
> - do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_FEATURES, 0, &nent,
> - cpuid->nent);
> -
> r = -E2BIG;
> - if (nent >= cpuid->nent)
> + if (i < ARRAY_SIZE(param) || nent > cpuid->nent)
> goto out_free;
>
Isn't the first condition sufficient?
The code may be more readable if do_cpuid_ent() (and do_cpuid_1_ent)
returned -E2BIG on overflow instead of all this cleverness.
--
error compiling committee.c: too many arguments to function
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