From: "Jan Beulich" <JBeulich@suse.com>
To: Julien Grall <julien.grall@arm.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 1/9] x86/hypercall: Move some of the hvm hypercall infrastructure into hypercall.h
Date: Tue, 02 Aug 2016 08:54:59 -0600 [thread overview]
Message-ID: <57A0D0630200007800101E25@prv-mh.provo.novell.com> (raw)
In-Reply-To: <582f0e7e-f210-226a-0ef8-057394486e78@arm.com>
>>> On 02.08.16 at 16:26, <julien.grall@arm.com> wrote:
>
> On 02/08/16 15:17, Jan Beulich wrote:
>>>>> On 02.08.16 at 16:04, <julien.grall@arm.com> wrote:
>>> On 02/08/16 14:28, Jan Beulich wrote:
>>>>>>> On 02.08.16 at 15:14, <andrew.cooper3@citrix.com> wrote:
>>>>> On 02/08/16 13:50, Jan Beulich wrote:
>>>>>>>>> On 18.07.16 at 11:51, <andrew.cooper3@citrix.com> wrote:
>>>>>>> #include <public/arch-x86/xen-mca.h> /* for do_mca */
>>>>>>> -#include <xen/types.h>
>>>>>>> +
>>>>>>> +typedef unsigned long hypercall_fn_t(
>>>>>>> + unsigned long, unsigned long, unsigned long,
>>>>>>> + unsigned long, unsigned long, unsigned long);
>>>>>> Wouldn't this better go into xen/hypercall.h?
>>>>>
>>>>> It is architecture specific.
>>>>>
>>>>> ARM's version is
>>>>>
>>>>> typedef register_t (*arm_hypercall_fn_t)(
>>>>> register_t, register_t, register_t, register_t, register_t);
>>>>
>>>> Which is bogus - they're lucky we so far don't have any 6-argument
>>>> hypercalls. Or the other way around - we could limit hypercalls to
>>>> just five arguments (for now) on x86 too, allowing things to get
>>>> unified. Anyway - that probably goes too far right now, so feel free
>>>> to add my ack to the patch.
>>>
>>> I am not sure why you think we are lucky on ARM. The hypercall has been
>>> defined on ARM to support up to 5 arguments (public/arch-arm.h):
>>>
>>> "A hypercall can take up to 5 arguments. These are passed in
>>> registers, the first argument in x0/r0 (for arm64/arm32 guests
>>> respectively irrespective of whether the underlying hypervisor is
>>> 32- or 64-bit), the second argument in x1/r1, the third in x2/r2,
>>> the forth in x3/r3 and the fifth in x4/r4."
>>>
>>> So the prototype matches the ABI.
>>
>> Well, I find it quite odd for hypercall argument counts to differ
>> between arches. I.e. I'd conclude the ABI was mis-specified.
>
> Is it documented somewhere for the x86 code? Looking at Linux, the
> privcmd call is only passing 5 arguments on both ARM and x86.
arch-x86/xen-x86_32.h has
* Hypercall interface:
* Input: %ebx, %ecx, %edx, %esi, %edi, %ebp (arguments 1-6)
* Output: %eax
while arch-x86/xen-x86_64.h has
* Hypercall interface:
* Input: %rdi, %rsi, %rdx, %r10, %r8, %r9 (arguments 1-6)
* Output: %rax
Jan
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next prev parent reply other threads:[~2016-08-02 14:54 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-18 9:51 [PATCH 0/9] x86: Move the pv hypercall into C Andrew Cooper
2016-07-18 9:51 ` [PATCH 1/9] x86/hypercall: Move some of the hvm hypercall infrastructure into hypercall.h Andrew Cooper
2016-08-02 12:50 ` Jan Beulich
2016-08-02 13:14 ` Andrew Cooper
2016-08-02 13:28 ` Jan Beulich
2016-08-02 14:04 ` Julien Grall
2016-08-02 14:17 ` Jan Beulich
2016-08-02 14:26 ` Julien Grall
2016-08-02 14:54 ` Jan Beulich [this message]
2016-08-02 14:59 ` Andrew Cooper
2016-08-02 15:05 ` Jan Beulich
2016-08-02 18:43 ` Stefano Stabellini
2016-08-03 8:53 ` Jan Beulich
2016-08-03 10:55 ` Julien Grall
2016-08-03 18:20 ` Stefano Stabellini
2016-08-04 11:27 ` Julien Grall
2016-07-18 9:51 ` [PATCH 2/9] x86/pv: Support do_set_segment_base() for compat guests Andrew Cooper
2016-08-02 12:52 ` Jan Beulich
2016-08-02 13:25 ` Andrew Cooper
2016-08-02 13:31 ` Jan Beulich
2016-08-02 13:39 ` Andrew Cooper
2016-08-02 13:47 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 3/9] x86/hypercall: Move the hypercall arg tables into C Andrew Cooper
2016-08-02 12:59 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 4/9] x86/pv: Implement pv_hypercall() in C Andrew Cooper
2016-08-02 13:12 ` Jan Beulich
2016-08-02 14:06 ` Andrew Cooper
2016-08-02 14:19 ` Jan Beulich
2016-08-11 11:57 ` Andrew Cooper
2016-08-11 12:20 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 5/9] x86/hypercall: Move the hypercall tables into C Andrew Cooper
2016-08-02 13:23 ` Jan Beulich
2016-08-02 13:30 ` Andrew Cooper
2016-08-02 13:40 ` Jan Beulich
2016-08-11 12:00 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 6/9] xen/multicall: Rework arch multicall handling Andrew Cooper
2016-07-20 12:35 ` Julien Grall
2016-08-03 15:02 ` Jan Beulich
2016-08-03 15:12 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 7/9] x86/pv: Merge the pv hypercall tables Andrew Cooper
2016-08-03 15:07 ` Jan Beulich
2016-08-11 12:36 ` Andrew Cooper
2016-07-18 9:51 ` [PATCH 8/9] x86/hypercall: Merge the hypercall arg tables Andrew Cooper
2016-08-03 15:12 ` Jan Beulich
2016-08-03 15:15 ` Andrew Cooper
2016-08-03 15:28 ` Jan Beulich
2016-07-18 9:51 ` [PATCH 9/9] x86/hypercall: Reduce the size of the hypercall tables Andrew Cooper
2016-08-03 15:17 ` Jan Beulich
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