From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 2/9] x86/pv: Support do_set_segment_base() for compat guests
Date: Tue, 2 Aug 2016 14:25:06 +0100 [thread overview]
Message-ID: <2b34bbf1-2fe1-ff46-fc57-a4130582da3d@citrix.com> (raw)
In-Reply-To: <57A0B3B60200007800101C53@prv-mh.provo.novell.com>
On 02/08/16 13:52, Jan Beulich wrote:
>>>> On 18.07.16 at 11:51, <andrew.cooper3@citrix.com> wrote:
>> set_segment_base is the only hypercall exists in only one of the two modes
>> guests might run in; all other hypercalls are either implemented, or
>> unimplemented in both modes.
>>
>> Remove this split, by allowing do_set_segment_base() to be called in the
>> compat hypercall path. This change will simplify the verification logic in a
>> later change.
>>
>> No behavioural change from a guests point of view.
> Nevertheless I don't view this as a reasonable change on its own:
Why not? It is far better to call it out in isolation, than to mix it
in with an already-existing complicated change.
>
>> --- a/xen/arch/x86/x86_64/compat/entry.S
>> +++ b/xen/arch/x86/x86_64/compat/entry.S
>> @@ -453,7 +453,7 @@ ENTRY(compat_hypercall_table)
>> .quad compat_update_va_mapping_otherdomain
>> .quad compat_iret
>> .quad compat_vcpu_op
>> - .quad compat_ni_hypercall /* 25 */
>> + .quad do_set_segment_base /* 25 */
> This part will (I suppose) be deleted by a later change.
When moved into C, it will be hidden behind the macros used to construct
both table values at once.
>
>> --- a/xen/arch/x86/x86_64/mm.c
>> +++ b/xen/arch/x86/x86_64/mm.c
>> @@ -1031,6 +1031,9 @@ long do_set_segment_base(unsigned int which, unsigned long base)
>> struct vcpu *v = current;
>> long ret = 0;
>>
>> + if ( is_pv_32bit_vcpu(v) )
>> + return -ENOSYS; /* x86/64 only. */
> And this addition could as well happen when that later change
> does the re-org.
Again, that would further complicate an already-complicated patch.
~Andrew
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next prev parent reply other threads:[~2016-08-02 13:25 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
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 [this message]
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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