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SubjectRe: [PATCH v5 04/17] x86/acrn: Introduce hypercall interfaces
On Mon, Oct 19, 2020 at 02:17:50PM +0800, shuo.a.liu@intel.com wrote:
> From: Shuo Liu <shuo.a.liu@intel.com>
>
> The Service VM communicates with the hypervisor via conventional
> hypercalls. VMCALL instruction is used to make the hypercalls.
>
> ACRN hypercall ABI:
> * Hypercall number is in R8 register.
> * Up to 2 parameters are in RDI and RSI registers.
> * Return value is in RAX register.
>
> Introduce the ACRN hypercall interfaces. Because GCC doesn't support R8
> register as direct register constraints, use supported constraint as
> input with a explicit MOV to R8 in beginning of asm.
>
> +static inline long acrn_hypercall0(unsigned long hcall_id)
> +{
> + long result;
> +
> + asm volatile("movl %1, %%r8d\n\t"
> + "vmcall\n\t"
> + : "=a" (result)
> + : "ir" (hcall_id)

Is the hypercall id an unsigned long (64 bits) or an unsigned int (32
bits)? This will generate broken assembly if the "r" option is chosen,
eg something like
movl %rdi, %r8d

> + : "r8", "memory");
> +
> + return result;
> +}
> +
> +static inline long acrn_hypercall1(unsigned long hcall_id,
> + unsigned long param1)
> +{
> + long result;
> +
> + asm volatile("movl %1, %%r8d\n\t"
> + "vmcall\n\t"
> + : "=a" (result)
> + : "ir" (hcall_id), "D" (param1)
> + : "r8", "memory");
> +
> + return result;
> +}
> +
> +static inline long acrn_hypercall2(unsigned long hcall_id,
> + unsigned long param1,
> + unsigned long param2)
> +{
> + long result;
> +
> + asm volatile("movl %1, %%r8d\n\t"
> + "vmcall\n\t"
> + : "=a" (result)
> + : "ir" (hcall_id), "D" (param1), "S" (param2)
> + : "r8", "memory");
> +
> + return result;
> +}
> +
> #endif /* _ASM_X86_ACRN_H */
> --
> 2.28.0
>

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