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From: "Alexandro Sanchez Bach" <alexandro@phi.nz>
To: 'Paolo Bonzini' <pbonzini@redhat.com>,
	'Markus Armbruster' <armbru@redhat.com>
Cc: "'Peter Maydell'" <peter.maydell@linaro.org>,
	"'Peter Krempa'" <pkrempa@redhat.com>,
	'Qemu-block' <qemu-block@nongnu.org>,
	'Libvirt' <libvir-list@redhat.com>,
	"'QEMU Developers'" <qemu-devel@nongnu.org>,
	"'László Érsek'" <lersek@redhat.com>,
	"'Justin Terry (VM)'" <juterry@microsoft.com>,
	"'Ning, Yu'" <yu.ning@intel.com>
Subject: Re: [Qemu-devel] Configuring pflash devices for OVMF firmware
Date: Fri, 1 Feb 2019 00:28:35 +0100	[thread overview]
Message-ID: <002701d4b9bc$b1fe72e0$15fb58a0$@phi.nz> (raw)
In-Reply-To: <cb465eba-8c54-af8e-fe0e-ce90f71d213a@redhat.com>

>> This is all greek to me.  I take it there's something wrong with these 
>> accelerators that makes (read-only?) flash memory not work, even 
>> though the read-only mapping we now create for traditional BIOS works.  
>> Weird, but I'm of course willing to take your word for it.

> Yes, as I wrote in the other message even read-only flash memory supports commands, and these accelerators do not support direct reads + MMIO writes on the same memory slot.
> At least I checked HAX code and it doesn't; I don't know about WHPX.

(CC'd Yu Ning @ Intel's HAXM team)

Not sure, if I'm understanding the issue correctly, but isn't `HAX_VM_IOCTL_SET_RAM2` with the `HAX_RAM_INFO_ROM` flag precisely what you are looking for?

More precisely, HAX_VM_IOCTL_SET_RAM2 maps an HVA range to a GPA range, the HAX_RAM_INFO_ROM flag should allow only guest memory reads to that range [1]. When the guest attempts to write, this should trigger a VM exit that will be handled by QEMU. Also, this seems to be handled here:
https://github.com/qemu/qemu/blob/15bede554162dda822cd762c689edb6fa32b6e3b/target/i386/hax-mem.c#L205-L207

Best,
Alexandro

[1] https://github.com/intel/haxm/blob/master/docs/api.md

  reply	other threads:[~2019-01-31 23:28 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-25 15:03 [Qemu-devel] Configuring pflash devices for OVMF firmware Markus Armbruster
2019-01-28  7:58 ` Laszlo Ersek
2019-01-28 10:39 ` Peter Maydell
2019-01-28 12:40   ` [Qemu-devel] [libvirt] " Gerd Hoffmann
2019-01-28 13:06     ` Peter Maydell
2019-01-28 14:55       ` Laszlo Ersek
2019-01-28 14:58         ` Peter Maydell
2019-01-28 15:03           ` Laszlo Ersek
2019-01-30  7:36       ` Markus Armbruster
2019-01-30  8:00         ` Gerd Hoffmann
2019-01-30  7:24   ` [Qemu-devel] " Markus Armbruster
2019-01-30 15:24     ` Peter Maydell
2019-01-30 16:44       ` Laszlo Ersek
2019-01-30 17:24         ` Peter Maydell
2019-01-31  8:52           ` Markus Armbruster
2019-01-31 10:01             ` Peter Maydell
2019-01-31 10:24               ` Markus Armbruster
2019-01-31 10:34                 ` Peter Maydell
2019-01-31 12:05                   ` Markus Armbruster
2019-01-30 14:13   ` Markus Armbruster
2019-01-30 14:33     ` Paolo Bonzini
2019-01-30 16:38       ` Laszlo Ersek
2019-01-31  8:33         ` Markus Armbruster
2019-01-31  9:19           ` Paolo Bonzini
2019-01-31  9:37             ` Markus Armbruster
2019-01-31 12:02               ` Laszlo Ersek
2019-01-31 12:10               ` Paolo Bonzini
2019-01-31 12:51                 ` Markus Armbruster
2019-01-31  8:40       ` Markus Armbruster
2019-01-31  9:19         ` Paolo Bonzini
2019-01-31  9:41           ` Markus Armbruster
2019-01-31 10:12             ` Paolo Bonzini
2019-01-31 12:12               ` Markus Armbruster
2019-01-31 22:57                 ` Paolo Bonzini
2019-01-31 23:28                   ` Alexandro Sanchez Bach [this message]
2019-01-31 23:54                     ` Paolo Bonzini
2019-02-01  2:49                       ` Ning, Yu
2019-02-04 10:00                         ` Paolo Bonzini
2019-02-01  8:58                   ` Markus Armbruster
2019-01-31 11:57           ` Laszlo Ersek
2019-02-19  7:19       ` Markus Armbruster
2019-02-22 13:28         ` Markus Armbruster
2019-02-07  9:30 ` Markus Armbruster
2019-02-07 12:31   ` Laszlo Ersek
2019-02-07 13:49     ` Markus Armbruster

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