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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Wei Liu <wl@xen.org>,
	Xen Development List <xen-devel@lists.xenproject.org>
Cc: "Michael Kelley" <mikelley@microsoft.com>,
	"Wei Liu" <liuwe@microsoft.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>,
	"Paul Durrant" <paul@xen.org>
Subject: Re: [Xen-devel] [PATCH v4 3/7] x86/hyperv: provide Hyper-V hypercall functions
Date: Wed, 22 Jan 2020 21:57:05 +0000	[thread overview]
Message-ID: <cb0e82dc-a154-f918-e725-f77913f835f9@citrix.com> (raw)
In-Reply-To: <20200122202343.5703-4-liuwe@microsoft.com>

On 22/01/2020 20:23, Wei Liu wrote:
> These functions will be used later to make hypercalls to Hyper-V.
>
> Signed-off-by: Wei Liu <liuwe@microsoft.com>

After some experimentation,

diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index cbc5701214..3708a60b5c 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -329,6 +329,8 @@ SECTIONS
   efi = .;
 #endif
 
+  hv_hcall_page = ABSOLUTE(0xffff82d0bfffe000);
+
   /* Sections to be discarded */
   /DISCARD/ : {
        *(.exit.text)

in the linker script lets direct calls work correctly:

ffff82d080637935:       b9 01 00 00 40          mov    $0x40000001,%ecx
ffff82d08063793a:       0f 30                   wrmsr 
ffff82d08063793c:       ba 21 03 00 00          mov    $0x321,%edx
ffff82d080637941:       bf 01 00 00 00          mov    $0x1,%edi
ffff82d080637946:       e8 ac 4f c7 ff          callq  ffff82d0802ac8f7
<__set_fixmap_x>
ffff82d08063794b:       41 b8 00 00 00 00       mov    $0x0,%r8d
ffff82d080637951:       b9 ff ff 00 00          mov    $0xffff,%ecx
ffff82d080637956:       ba 00 00 00 00          mov    $0x0,%edx
ffff82d08063795b:       e8 a0 66 9c 3f          callq  ffff82d0bfffe000
<hv_hcall_page>
ffff82d080637960:       66 83 f8 02             cmp    $0x2,%ax

but it does throw:

Difference at .init:00032edf is 0xc0000000 (expected 0x40000000)
Difference at .init:00032edf is 0xc0000000 (expected 0x40000000)

as a diagnostic presumably from the final link  (both with a standard
Debian 2.28 binutils, and upstream 2.33 build).  I'm not sure what its
trying to complain about, as both xen.gz and xen.efi have correctly
generated code.

Depending on whether they are benign or not, a linker-friendly
fix_to_virt() should be all we need to keep these strictly as direct calls.

~Andrew

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  reply	other threads:[~2020-01-22 21:57 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-22 20:23 [Xen-devel] [PATCH v4 0/7] More Hyper-V infrastructure Wei Liu
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 1/7] x86: provide executable fixmap facility Wei Liu
2020-01-22 20:56   ` Andrew Cooper
2020-01-28 15:09     ` Wei Liu
2020-01-23 11:04   ` Jan Beulich
2020-01-28 15:15     ` Wei Liu
2020-01-28 15:38       ` Jan Beulich
2020-01-29 14:42         ` Wei Liu
2020-01-29 14:59           ` Jan Beulich
2020-01-29 16:37             ` Wei Liu
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 2/7] x86/hyperv: setup hypercall page Wei Liu
2020-01-22 21:31   ` Andrew Cooper
2020-01-23 10:04     ` Jan Beulich
2020-01-28 15:19     ` Wei Liu
2020-01-23  1:35   ` Michael Kelley
2020-01-28 15:20     ` Wei Liu
2020-01-23 11:18   ` Jan Beulich
2020-01-23 15:20     ` Michael Kelley
2020-01-28 15:30     ` Wei Liu
2020-01-28 15:41       ` Jan Beulich
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 3/7] x86/hyperv: provide Hyper-V hypercall functions Wei Liu
2020-01-22 21:57   ` Andrew Cooper [this message]
2020-01-23 10:13     ` Jan Beulich
2020-01-29 18:25       ` Wei Liu
2020-01-23 11:28   ` Jan Beulich
2020-01-29 18:37     ` Wei Liu
2020-01-30  8:12       ` Jan Beulich
2020-01-30 11:55         ` Wei Liu
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 4/7] DO NOT APPLY: x86/hyperv: issue an hypercall Wei Liu
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 5/7] x86/hyperv: provide percpu hypercall input page Wei Liu
2020-01-23 15:45   ` Jan Beulich
2020-01-28 15:50     ` Wei Liu
2020-01-28 16:15       ` Jan Beulich
2020-01-28 16:52         ` Wei Liu
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 6/7] x86/hyperv: retrieve vp_index from Hyper-V Wei Liu
2020-01-23 15:48   ` Jan Beulich
2020-01-28 15:55     ` Wei Liu
2020-01-28 16:18       ` Jan Beulich
2020-01-28 16:33         ` Durrant, Paul
2020-01-28 16:53           ` Wei Liu
2020-01-28 17:01             ` Durrant, Paul
2020-01-22 20:23 ` [Xen-devel] [PATCH v4 7/7] x86/hyperv: setup VP assist page Wei Liu
2020-01-22 22:05   ` Andrew Cooper
2020-01-23 15:50   ` Jan Beulich

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