linux-kernel - Re: [PATCH v3 2/7] Drivers: hv: Enable VTL mode for arm64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240805040503.GA14919@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Sun, 4 Aug 2024 21:05:03 -0700
From: Saurabh Singh Sengar <ssengar@...ux.microsoft.com>
To: Michael Kelley <mhklinux@...look.com>
Cc: Roman Kisel <romank@...ux.microsoft.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>,
	"bp@...en8.de" <bp@...en8.de>,
	"catalin.marinas@....com" <catalin.marinas@....com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"decui@...rosoft.com" <decui@...rosoft.com>,
	"haiyangz@...rosoft.com" <haiyangz@...rosoft.com>,
	"hpa@...or.com" <hpa@...or.com>, "kw@...ux.com" <kw@...ux.com>,
	"kys@...rosoft.com" <kys@...rosoft.com>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"lpieralisi@...nel.org" <lpieralisi@...nel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"rafael@...nel.org" <rafael@...nel.org>,
	"robh@...nel.org" <robh@...nel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"wei.liu@...nel.org" <wei.liu@...nel.org>,
	"will@...nel.org" <will@...nel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"apais@...rosoft.com" <apais@...rosoft.com>,
	"benhill@...rosoft.com" <benhill@...rosoft.com>,
	"ssengar@...rosoft.com" <ssengar@...rosoft.com>,
	"sunilmut@...rosoft.com" <sunilmut@...rosoft.com>,
	"vdso@...bites.dev" <vdso@...bites.dev>
Subject: Re: [PATCH v3 2/7] Drivers: hv: Enable VTL mode for arm64

On Mon, Aug 05, 2024 at 03:01:58AM +0000, Michael Kelley wrote:
> From: Roman Kisel <romank@...ux.microsoft.com> Sent: Friday, July 26, 2024 3:59 PM
> > 
> > Kconfig dependencies for arm64 guests on Hyper-V require that be ACPI enabled,
> > and limit VTL mode to x86/x64. To enable VTL mode on arm64 as well, update the
> > dependencies. Since VTL mode requires DeviceTree instead of ACPI, don't require
> > arm64 guests on Hyper-V to have ACPI.
> > 
> > Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
> > ---
> >  drivers/hv/Kconfig | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> > index 862c47b191af..a5cd1365e248 100644
> > --- a/drivers/hv/Kconfig
> > +++ b/drivers/hv/Kconfig
> > @@ -5,7 +5,7 @@ menu "Microsoft Hyper-V guest support"
> >  config HYPERV
> >  	tristate "Microsoft Hyper-V client drivers"
> >  	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
> > -		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
> > +		|| (ARM64 && !CPU_BIG_ENDIAN)
> >  	select PARAVIRT
> >  	select X86_HV_CALLBACK_VECTOR if X86
> >  	select OF_EARLY_FLATTREE if OF
> > @@ -15,7 +15,7 @@ config HYPERV
> > 
> >  config HYPERV_VTL_MODE
> >  	bool "Enable Linux to boot in VTL context"
> > -	depends on X86_64 && HYPERV
> > +	depends on HYPERV
> >  	depends on SMP
> >  	default n
> >  	help
> > @@ -31,7 +31,7 @@ config HYPERV_VTL_MODE
> > 
> >  	  Select this option to build a Linux kernel to run at a VTL other than
> >  	  the normal VTL0, which currently is only VTL2.  This option
> > -	  initializes the x86 platform for VTL2, and adds the ability to boot
> > +	  initializes the kernel to run in VTL2, and adds the ability to boot
> >  	  secondary CPUs directly into 64-bit context as required for VTLs other
> >  	  than 0.  A kernel built with this option must run at VTL2, and will
> >  	  not run as a normal guest.
> > --
> > 2.34.1
> > 
> 
> In v2 of this patch, I suggested [1] making a couple additional minor changes
> so that kernels built *without* HYPER_VTL_MODE would still require
> ACPI.  Did that suggestion not work out?  If that's the case, I'm curious
> about what goes wrong.

Hi Michael/Roman,
I was considering making HYPERV_VTL_MODE depend on CONFIG_OF. That should address
above concern as well. Do you see any potential issue with it.

- Saurabh