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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Fenghua Yu <fenghua.yu@intel.com>
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
In-Reply-To: <20200427221825.GF242333@romley-ivt3.sc.intel.com>
References: <1585596788-193989-1-git-send-email-fenghua.yu@intel.com> <1585596788-193989-6-git-send-email-fenghua.yu@intel.com> <87pnbus3du.fsf@nanos.tec.linutronix.de> <20200427221825.GF242333@romley-ivt3.sc.intel.com>
Date:   Tue, 28 Apr 2020 01:44:21 +0200
Message-ID: <87d07spk8a.fsf@nanos.tec.linutronix.de>
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Fenghua Yu <fenghua.yu@intel.com> writes:
> On Sun, Apr 26, 2020 at 04:55:25PM +0200, Thomas Gleixner wrote:
>> Fenghua Yu <fenghua.yu@intel.com> writes:
>> > + +#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.
>
> The pasid is defined as "int" in struct intel_svm and in 
> intel_svm_bind_mm() and intel_svm_unbind_mm(). So the pasid defined in this 
> patch follows the same type defined in those places.

Which are wrong to begin with.

>> ioasid_alloc() uses ioasid_t which is
>> 
>> typedef unsigned int ioasid_t;
>> 
>> Can we please have consistent types and behaviour all over the place?
>
> Should I just define "pasid", "pasid_max", "flags" as "unsigned int" for
> the new functions/code?
>
> Or should I also change their types to "unsigned int" in the original
> svm code (struct intel_svm, ...bind_mm(), etc)? I'm afraid that will be
> a lot of changes and should be in a separate preparation patch.

Yes, please. The existance of non-sensical code is not an excuse to
proliferate it.

Thanks,

        tglx