linux-kernel - Re: [Xen-devel] HVMLite / PVHv2

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Message-ID: <20160413102157.GK2829@codeblueprint.co.uk>
Date:	Wed, 13 Apr 2016 11:21:57 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Roger Pau Monné <roger.pau@...rix.com>
Cc:	George Dunlap <george.dunlap@...rix.com>,
	Michael Chang <MChang@...e.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Julien Grall <julien.grall@....com>,
	Jan Beulich <JBeulich@...e.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Vojtěch Pavlík <vojtech@...e.cz>,
	Gary Lin <GLin@...e.com>,
	xen-devel <xen-devel@...ts.xenproject.org>,
	Jeffrey Cheung <JCheung@...e.com>,
	Charles Arndol <carnold@...e.com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	joeyli <jlee@...e.com>, Borislav Petkov <bp@...en8.de>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Juergen Gross <jgross@...e.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Jim Fehlig <jfehlig@...e.com>,
	Andy Lutomirski <luto@...capital.net>,
	"Luis R. Rodriguez" <mcgrof@...nel.org>,
	David Vrabel <david.vrabel@...rix.com>
Subject: Re: [Xen-devel] HVMLite / PVHv2 - using x86 EFI boot entry

On Wed, 13 Apr, at 12:03:12PM, Roger Pau Monné wrote:
> 
> I don't get this, the "reset/shutdown" hypercall requires the following 
> steps from Dom0 (it's not as simple as calling a hypercall):
> 
> The way to perform a full system power off from Dom0 is different than 
> what's done in a DomU guest. In order to perform a power off from Dom0 the 
> native ACPI path should be followed, but the guest should not write the 
> `SLP_EN` bit to the Pm1Control register. Instead the 
> `XENPF_enter_acpi_sleep` hypercall should be used, filling the following 
> data in the `xen_platform_op` struct:
> 
>     cmd = XENPF_enter_acpi_sleep
>     interface_version = XENPF_INTERFACE_VERSION
>     u.enter_acpi_sleep.pm1a_cnt_val = Pm1aControlValue
>     u.enter_acpi_sleep.pm1b_cnt_val = Pm1bControlValue
> 
> At which point it means that we are either going to duplicate ACPICA code 
> into the HVMlite's custom EfiReset() service, or we are going to call into 
> ACPICA, which is what we already do now.

Fair enough, I wasn't aware that you needed to call into ACPI to
perform the reset.