Re: [PATCH 5/7] x86/mmu: Allocate/free PASID

From: Fenghua Yu <fenghua.yu@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	H Peter Anvin <hpa@zytor.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>, Ashok Raj <ashok.raj@intel.com>,
	Jacob Jun Pan <jacob.jun.pan@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Sohil Mehta <sohil.mehta@intel.com>,
	Ravi V Shankar <ravi.v.shankar@intel.com>,
	linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
	iommu@lists.linux-foundation.org
Subject: Re: [PATCH 5/7] x86/mmu: Allocate/free PASID
Date: Tue, 28 Apr 2020 13:57:19 -0700	[thread overview]
Message-ID: <20200428205718.GG242333@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <87pnbus3du.fsf@nanos.tec.linutronix.de>

On Sun, Apr 26, 2020 at 04:55:25PM +0200, Thomas Gleixner wrote:
> Fenghua Yu <fenghua.yu@intel.com> writes:
> > diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
> > index bdeae9291e5c..137bf51f19e6 100644
> > --- a/arch/x86/include/asm/mmu.h
> > +++ b/arch/x86/include/asm/mmu.h
> > @@ -50,6 +50,10 @@ typedef struct {
> >  	u16 pkey_allocation_map;
> >  	s16 execute_only_pkey;
> >  #endif
> > +
> > +#ifdef CONFIG_INTEL_IOMMU_SVM
> > +	int pasid;
> 
> int? It's a value which gets programmed into the MSR along with the
> valid bit (bit 31) set. 

BTW, ARM is working on PASID as well. Christoph suggested that the PASID
should be defined in mm_struct instead of mm->context so that both ARM and X86
can access it:
https://lore.kernel.org/linux-iommu/20200414170252.714402-1-jean-philippe@linaro.org/T/#mb57110ffe1aaa24750eeea4f93b611f0d1913911

So I will define "pasid" to mm_struct in a separate patch in the next version.

Thanks.

-Fenghua