On Mon 19.Oct'20 at 18:15:15 -0400, Arvind Sankar wrote:
On Mon, Oct 19, 2020 at 02:17:50PM +0800, [email protected] wrote:
From: Shuo Liu <[email protected]>
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
Yes, it can be an unsigned long. So do MOV explicitly.
asm volatile("movq %1, %%r8\n\t"
"vmcall\n\t"
: "=a" (result)
: "ir" (hcall_id)
Thanks
