From: Thomas Gleixner <[email protected]>
Provide a few helper functions to read CPUID leafs or individual registers
into a data structure without requiring unions.
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Juergen Gross <[email protected]>
Tested-by: Sohil Mehta <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Tested-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Zhang Rui <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
---
arch/x86/include/asm/cpuid.h | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
---
--- a/arch/x86/include/asm/cpuid.h
+++ b/arch/x86/include/asm/cpuid.h
@@ -127,6 +127,42 @@ static inline unsigned int cpuid_edx(uns
return edx;
}
+static inline void __cpuid_read(unsigned int leaf, unsigned int subleaf, u32 *regs)
+{
+ regs[CPUID_EAX] = leaf;
+ regs[CPUID_ECX] = subleaf;
+ __cpuid(regs, regs + 1, regs + 2, regs + 3);
+}
+
+#define cpuid_subleaf(leaf, subleaf, regs) { \
+ BUILD_BUG_ON(sizeof(*(regs)) != 16); \
+ __cpuid_read(leaf, subleaf, (u32 *)(regs)); \
+}
+
+#define cpuid_leaf(leaf, regs) { \
+ BUILD_BUG_ON(sizeof(*(regs)) != 16); \
+ __cpuid_read(leaf, 0, (u32 *)(regs)); \
+}
+
+static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
+ enum cpuid_regs_idx regidx, u32 *reg)
+{
+ u32 regs[4];
+
+ __cpuid_read(leaf, subleaf, regs);
+ *reg = regs[regidx];
+}
+
+#define cpuid_subleaf_reg(leaf, subleaf, regidx, reg) { \
+ BUILD_BUG_ON(sizeof(*(reg)) != 4); \
+ __cpuid_read_reg(leaf, subleaf, regidx, (u32 *)(reg)); \
+}
+
+#define cpuid_leaf_reg(leaf, regidx, reg) { \
+ BUILD_BUG_ON(sizeof(*(reg)) != 4); \
+ __cpuid_read_reg(leaf, 0, regidx, (u32 *)(reg)); \
+}
+
static __always_inline bool cpuid_function_is_indexed(u32 function)
{
switch (function) {
On Tue, Jan 23, 2024 at 01:53:30PM +0100, Thomas Gleixner wrote:
> +static inline void __cpuid_read(unsigned int leaf, unsigned int subleaf, u32 *regs)
> +{
> + regs[CPUID_EAX] = leaf;
> + regs[CPUID_ECX] = subleaf;
> + __cpuid(regs, regs + 1, regs + 2, regs + 3);
You have defines for the regs - might as well use them:
__cpuid(regs, regs + CPUID_EBX, regs + CPUID_ECX, regs + CPUID_EDX);
> +}
> +
> +#define cpuid_subleaf(leaf, subleaf, regs) { \
> + BUILD_BUG_ON(sizeof(*(regs)) != 16); \
> + __cpuid_read(leaf, subleaf, (u32 *)(regs)); \
> +}
> +
> +#define cpuid_leaf(leaf, regs) { \
> + BUILD_BUG_ON(sizeof(*(regs)) != 16); \
> + __cpuid_read(leaf, 0, (u32 *)(regs)); \
> +}
> +
> +static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
> + enum cpuid_regs_idx regidx, u32 *reg)
> +{
> + u32 regs[4];
> +
> + __cpuid_read(leaf, subleaf, regs);
> + *reg = regs[regidx];
Why not do
return regs[regidx];
instead?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Jan 24, 2024 at 01:25:12PM +0100, Borislav Petkov wrote:
> > +static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
> > + enum cpuid_regs_idx regidx, u32 *reg)
> > +{
> > + u32 regs[4];
> > +
> > + __cpuid_read(leaf, subleaf, regs);
> > + *reg = regs[regidx];
>
> Why not do
>
> return regs[regidx];
>
> instead?
Or do you really want to be able to use anonymous structs with bitfields
in them and then convert them to a u32 * when passing in to
cpuid_leaf_reg() etc in order to save yourself all the masking and
shifting and read out the bitfields directly?
I'm looking at the parse_topology() use case.
Looks like it...
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Jan 24 2024 at 21:02, Borislav Petkov wrote:
> On Wed, Jan 24, 2024 at 01:25:12PM +0100, Borislav Petkov wrote:
>> > +static inline void __cpuid_read_reg(unsigned int leaf, unsigned int subleaf,
>> > + enum cpuid_regs_idx regidx, u32 *reg)
>> > +{
>> > + u32 regs[4];
>> > +
>> > + __cpuid_read(leaf, subleaf, regs);
>> > + *reg = regs[regidx];
>>
>> Why not do
>>
>> return regs[regidx];
>>
>> instead?
>
> Or do you really want to be able to use anonymous structs with bitfields
> in them and then convert them to a u32 * when passing in to
> cpuid_leaf_reg() etc in order to save yourself all the masking and
> shifting and read out the bitfields directly?
>
> I'm looking at the parse_topology() use case.
>
> Looks like it...
Yes, that's the idea.