[svsm-devel] [PATCH v3 02/14] x86/sev: Make the VMPL0 checking function more generic

[Borislav Petkov]

On Mon, Mar 25, 2024 at 05:26:21PM -0500, Tom Lendacky wrote:
> -static void enforce_vmpl0(void)
> +static bool running_at_vmpl0(void *va)

Not too crazy about it: you're turning it into a function which runs in
boolean context but takes a void *?!

And the boolean result is only a side-effect or what it does to the
argument - modify its permissions. Which is weird and not really
obvious.

I'd prefer it if you made it into

static void vmpl0_modify_permissions(void *va)

which basically says, modify the permissions of @va in vmpl0, which is
a lot closer to what the function does.

And then do

#define running_at_vmpl0(va)	vmpl0_modify_permissions((va))

because then through the indirection is at least clear how that "am
I running at VMPL0?" check is being done.

And later, if we need other VMPLs, we can extend
vmpl0_modify_permissions() and even do a more generic

vmpl_modify_permissions(unsigned int vmpl_level, void *va)

and so on and kill the silly macro.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette