From: "Anthony PERARD" <anthony.perard@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Laszlo Ersek" <lersek@redhat.com>,
devel@edk2.groups.io, xen-devel@lists.xenproject.org,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Jordan Justen" <jordan.l.justen@intel.com>,
"Julien Grall" <julien.grall@arm.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH v3 06/35] OvmfPkg/XenResetVector: Add new entry point for Xen PVH
Date: Fri, 19 Jul 2019 16:51:04 +0100 [thread overview]
Message-ID: <20190719155104.GD1208@perard.uk.xensource.com> (raw)
In-Reply-To: <c2f583f7-a88c-010a-115d-2df4457dba5e@citrix.com>
On Fri, Jul 19, 2019 at 03:41:52PM +0100, Andrew Cooper wrote:
> On 19/07/2019 15:33, Laszlo Ersek wrote:
> > On 07/19/19 12:20, Anthony PERARD wrote:
> >> On Fri, Jul 05, 2019 at 02:57:06PM +0100, Andrew Cooper wrote:
> >>> On 04/07/2019 15:42, Anthony PERARD wrote:
> >>>> diff --git a/OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm b/OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm
> >>>> new file mode 100644
> >>>> index 0000000000..958195bc5e
> >>>> --- /dev/null
> >>>> +++ b/OvmfPkg/XenResetVector/Ia16/ResetVectorVtf0.asm
> >>>> +vtfSignature:
> >>>> + DB 'V', 'T', 'F', 0
> >>>> +
> >>>> +ALIGN 16
> >>>> +
> >>>> +resetVector:
> >>>> +;
> >>>> +; Reset Vector
> >>>> +;
> >>>> +; This is where the processor will begin execution
> >>>> +;
> >>>> + nop
> >>>> + nop
> >>> Why two nops?
> >> I don't know, this is existing code that I duplicated to allow adding a
> >> new entry point. (I wanted to use --find-copies-harder when sending the
> >> patch, but forgot this time.
> > Not a big problem; while reviewing v3, I did such comparisons myself, in
> > my local clone. Feel free to skip "--find-copies-harder" when posting v4
> > too; I think there isn't much churn going on in parallel right now.
> >
> > However, a new request for v4: please make sure that the new modules /
> > paths introduced by this patch set are covered in Maintainers.txt.
Will do.
> >> This part of the chunk would not be there.)
> > Regarding the NOPs: all I can tell you is that they originate from
> > commit 8332983e2e33 ("UefiCpuPkg: Replace the un-necessary WBINVD
> > instruction at the reset vector with two NOPs in VTF0.", 2011-08-04).
> >
> > Whether that change made sense back then, let alone if it makes sense
> > now: no clue.
>
> Dropping wbinvd makes sense, because when virtualised, the caches (and
> paging for that matter) are always up and running correctly. Its an
> unnecessary vmexit for something which the hypervisor will nop out anyway.
>
> Leaving two nops behind makes no sense at all.
I'll remove the nops.
Thanks,
--
Anthony PERARD
next prev parent reply other threads:[~2019-07-19 15:51 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-04 14:41 [PATCH v3 00/35] Specific platform to run OVMF in Xen PVH and HVM guests Anthony PERARD
2019-07-04 14:41 ` [PATCH v3 01/35] OvmfPkg/ResetSystemLib: Add missing dependency on PciLib Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 02/35] OvmfPkg: Create platform OvmfXen Anthony PERARD
2019-07-05 13:29 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 03/35] OvmfPkg: Introduce XenResetVector Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 04/35] OvmfPkg: Introduce XenPlatformPei Anthony PERARD
2019-07-05 13:53 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 05/35] OvmfPkg/OvmfXen: Creating an ELF header Anthony PERARD
2019-07-05 14:09 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 06/35] OvmfPkg/XenResetVector: Add new entry point for Xen PVH Anthony PERARD
2019-07-05 13:57 ` Andrew Cooper
2019-07-19 10:20 ` Anthony PERARD
2019-07-19 14:33 ` Laszlo Ersek
2019-07-19 14:41 ` Andrew Cooper
2019-07-19 15:51 ` Anthony PERARD [this message]
2019-07-05 14:14 ` Laszlo Ersek
2019-07-15 11:46 ` Roger Pau Monné
2019-07-15 11:50 ` Andrew Cooper
2019-07-15 14:25 ` Roger Pau Monné
2019-07-19 14:00 ` Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 07/35] OvmfPkg/XenResetVector: Saving start of day pointer for PVH guests Anthony PERARD
2019-07-05 14:24 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 08/35] OvmfPkg/XenResetVector: Allow jumpstart from either hvmloader or PVH Anthony PERARD
2019-07-05 14:54 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 09/35] OvmfPkg/OvmfXen: use a TimerLib instance that depends only on the CPU Anthony PERARD
2019-07-05 15:01 ` Laszlo Ersek
2019-07-15 14:22 ` Roger Pau Monné
2019-07-22 13:49 ` Anthony PERARD
2019-07-22 19:28 ` Laszlo Ersek
2019-07-23 9:02 ` Roger Pau Monné
2019-07-04 14:42 ` [PATCH v3 10/35] OvmfPkg/XenPlatformPei: Detect OVMF_INFO from hvmloader Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 11/35] OvmfPkg/XenPlatformPei: Use mXenHvmloaderInfo to get E820 Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 12/35] OvmfPkg/XenPlatformPei: Grab RSDP from PVH guest start of day struct Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 13/35] OvmfPkg/Library/XenPlatformLib: New library Anthony PERARD
2019-07-08 14:34 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 14/35] OvmfPkg/AcpiPlatformDxe: Use XenPlatformLib Anthony PERARD
2019-07-08 14:38 ` Laszlo Ersek
2019-07-10 9:42 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 15/35] OvmfPkg/AcpiPlatformDxe: Use Xen PVH RSDP if it exist Anthony PERARD
2019-07-08 14:42 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 16/35] OvmfPkg/XenHypercallLib: Enable it in PEIM Anthony PERARD
2019-07-08 14:51 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 17/35] OvmfPkg/XenPlatformPei: Reinit XenHypercallLib Anthony PERARD
2019-07-08 15:07 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 18/35] OvmfPkg/XenPlatformPei: Introduce XenHvmloaderDetected Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 19/35] OvmfPkg/XenPlatformPei: Reserve hvmloader's memory only when it has run Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 20/35] OvmfPkg/XenPlatformPei: Setup HyperPages earlier Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 21/35] OvmfPkg/XenPlatformPei: Introduce XenPvhDetected Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 22/35] OvmfPkg: Import XENMEM_memory_map hypercall to Xen/memory.h Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 23/35] OvmfPkg/XenPlatformPei: no hvmloader: get the E820 table via hypercall Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 24/35] OvmfPkg/XenPlatformPei: Rework memory detection Anthony PERARD
2019-07-15 14:15 ` roger.pau
2019-07-22 14:53 ` Anthony PERARD
2019-07-22 19:45 ` Laszlo Ersek
2019-07-22 23:08 ` Laszlo Ersek
2019-07-23 9:42 ` Roger Pau Monné
2019-07-23 16:06 ` Anthony PERARD
2019-07-24 16:17 ` Anthony PERARD
2019-07-25 9:08 ` Roger Pau Monné
2019-07-25 10:05 ` Anthony PERARD
2019-07-25 11:03 ` Roger Pau Monné
2019-07-04 14:42 ` [PATCH v3 25/35] OvmfPkg/XenPlatformPei: Reserve VGA memory region, to boot Linux Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 26/35] OvmfPkg/XenPlatformPei: Ignore missing PCI Host Bridge on Xen PVH Anthony PERARD
2019-07-08 15:31 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 27/35] OvmfPkg/XenPlatformLib: Cache result for XenDetected Anthony PERARD
2019-07-10 9:31 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 28/35] OvmfPkg/PlatformBootManagerLib: Use XenDetected from XenPlatformLib Anthony PERARD
2019-07-10 9:45 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 29/35] OvmfPkg/PlatformBootManagerLib: Handle the absence of PCI bus on Xen PVH Anthony PERARD
2019-07-10 9:50 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 30/35] OvmfPkg/OvmfXen: Override PcdFSBClock to Xen vLAPIC timer frequency Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 31/35] OvmfPkg/OvmfXen: Introduce XenTimerDxe Anthony PERARD
2019-07-10 10:12 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 32/35] OvmfPkg/PlatformBootManagerLib: Use a Xen console for ConOut/ConIn Anthony PERARD
2019-07-10 10:48 ` Laszlo Ersek
2019-07-22 17:06 ` Anthony PERARD
2019-07-23 7:31 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 33/35] OvmfPkg: Introduce XenIoPvhDxe to initialize Grant Tables Anthony PERARD
2019-07-10 14:05 ` Laszlo Ersek
2019-07-26 16:06 ` Anthony PERARD
2019-07-26 17:19 ` Laszlo Ersek
2019-07-04 14:42 ` [PATCH v3 34/35] OvmfPkg: Move XenRealTimeClockLib from ArmVirtPkg Anthony PERARD
2019-07-04 14:42 ` [PATCH v3 35/35] OvmfPkg/OvmfXen: use RealTimeClockRuntimeDxe from EmbeddedPkg Anthony PERARD
2019-07-05 12:21 ` [edk2-devel] [PATCH v3 00/35] Specific platform to run OVMF in Xen PVH and HVM guests Laszlo Ersek
2019-07-19 16:42 ` Anthony PERARD
2019-07-22 19:09 ` Laszlo Ersek
2019-07-23 11:37 ` Anthony PERARD
2019-07-30 9:03 ` Laszlo Ersek
2019-07-05 15:06 ` Laszlo Ersek
2019-07-10 14:12 ` Laszlo Ersek
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