Re: [PATCH 2/2] KVM: selftests: Test forced instruction emulation in dirty log test (x86 only)

From: Oliver Upton
Date: Thu Feb 15 2024 - 18:27:53 EST


On Thu, Feb 15, 2024 at 01:33:48PM -0800, Sean Christopherson wrote:

[...]

> +/* TODO: Expand this madness to also support u8, u16, and u32 operands. */
> +#define vcpu_arch_put_guest(mem, val, rand) \
> +do { \
> + if (!is_forced_emulation_enabled || !(rand & 1)) { \
> + *mem = val; \
> + } else if (rand & 2) { \
> + __asm__ __volatile__(KVM_FEP "movq %1, %0" \
> + : "+m" (*mem) \
> + : "r" (val) : "memory"); \
> + } else { \
> + uint64_t __old = READ_ONCE(*mem); \
> + \
> + __asm__ __volatile__(KVM_FEP LOCK_PREFIX "cmpxchgq %[new], %[ptr]" \
> + : [ptr] "+m" (*mem), [old] "+a" (__old) \
> + : [new]"r" (val) : "memory", "cc"); \
> + } \
> +} while (0)
> +

Last bit of bikeshedding then I'll go... Can you just use a C function
and #define it so you can still do ifdeffery to slam in a default
implementation?

I hate macros :)

--
Thanks,
Oliver