Messages in this thread | | | From | Arvind Sankar <> | Date | Mon, 19 Oct 2020 22:08:51 -0400 | Subject | Re: [PATCH v5 04/17] x86/acrn: Introduce hypercall interfaces |
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On Tue, Oct 20, 2020 at 09:38:09AM +0800, Shuo A Liu wrote: > On Mon 19.Oct'20 at 18:15:15 -0400, Arvind Sankar wrote: > >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 > > 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
All the hypercall ID's defined seem to be only 32 bits though?
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