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cpu: cache the maximum input value for CPUID extended function

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Per SDM:

    When CPUID executes with EAX set to 80000000H, the processor returns
    the highest value the processor recognizes for returning extended
    processor information. The value is returned in the EAX register and is
    processor specific.

This patch caches this value in the global cpuinfo_x86.cpuid_leaves. This
value will be used to check the availability of any CPUID extended
function.

Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
This commit is contained in:
Junjie Mao
2018-04-02 23:51:49 +08:00
committed by lijinxia
parent d0ce6a9fc6
commit 802080e348
3 changed files with 10 additions and 1 deletions
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7
arch/x86/cpu.c
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@@ -128,6 +128,7 @@ inline bool get_vmx_cap(void)
static void get_cpu_capabilities(void)
{
uint32_t eax, unused;
uint32_t max_extended_function_idx;
uint32_t family, model;
cpuid(CPUID_FEATURES, &eax, &unused,
@@ -149,6 +150,12 @@ static void get_cpu_capabilities(void)
&boot_cpu_data.cpuid_leaves[FEAT_7_0_ECX],
&boot_cpu_data.cpuid_leaves[FEAT_7_0_EDX]);
cpuid(CPUID_MAX_EXTENDED_FUNCTION,
&max_extended_function_idx,
&unused, &unused, &unused);
boot_cpu_data.cpuid_leaves[FEAT_8000_0000_EAX] =
max_extended_function_idx;
cpuid(CPUID_EXTEND_FUNCTION_1, &unused, &unused,
&boot_cpu_data.cpuid_leaves[FEAT_8000_0001_ECX],
&boot_cpu_data.cpuid_leaves[FEAT_8000_0001_EDX]);