Messages in this thread | | | Subject | Re: [RFC PATCH v2 3/3] arch/x86/acrn: add hypercall for acrn_guest | From | "Zhao, Yakui" <> | Date | Mon, 8 Apr 2019 11:31:48 +0800 |
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On 2019年04月06日 03:19, Thomas Gleixner wrote: > On Tue, 26 Mar 2019, Zhao Yakui wrote: > >> When acrn_hypervisor is detected, the hypercall is needed so that the >> acrn guest can query/config some settings. For example: it can be used >> to query the resources in hypervisor and manage the CPU/memory/device/ >> interrupt for Guest system. >> >> So the hypercall is added so that the kernel can communicate with the >> low-level acrn-hypervisor. On x86 it is implemented by using vmacll when > > is implemented with the VMCALL instruction > >> the acrn hypervisor is enabled. >> >> +++ b/arch/x86/include/asm/acrn_hypercall.h >> @@ -0,0 +1,84 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * acrn_hypercall.h : acrn hypervisor call API > > No file names in headers please. They are pointless and get out of sync > when files are renamed.
Sure. It will be removed in next vesion.
> >> + */ >> + >> +#ifndef __ACRN_HYPERCALL_H__ >> +#define __ACRN_HYPERCALL_H__ > > asm headers start with > > __ASM_X86_.... > This will be fixed.
>> + >> +#include <linux/errno.h> >> + >> +#ifdef CONFIG_ACRN_GUEST >> + >> +/* >> + * Hypercalls for ACRN Guest >> + * >> + * Hypercall number is passed in r8 register. >> + * Return value will be placed in rax. >> + * Up to 2 arguments are passed in rdi, rsi. >> + */ >> + >> +static inline long acrn_hypercall0(unsigned long hcall_id) >> +{ >> + > > Remove the empty new line please. > >> + register long result asm("rax"); >> + register unsigned long r8 asm("r8") = hcall_id; > > Please order them the other way around, like a reverse christmas tree: > > register unsigned long r8 asm("r8") = hcall_id; > register long result asm("rax"); > > That's way simpler to read.
This will be fixed.
> >> + asm volatile(".byte 0x0F,0x01,0xC1\n" >> + : "=r"(result) >> + : "r"(r8)); > > Please mention in the changelog why this is implemented with bytes and not > with the proper mnemonic. I assume it depends on binutils, so please > document which version of binutils supports the mnemonic.
I check the binutils version mentioned in Document/changes. (binutils, 2.20) It seems that the "vmcall" is already supported. So the "vmcall" mnemonic will be used to make it readable.
> > And in the first function, i.e. hypercall0, add a comment above the asm > volatile() to that effect as well.
Sure.
> > Thanks, > > tglx >
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