linux-kernel - Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID allocation and free it on mm exit

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Date:   Fri, 15 Apr 2022 05:37:34 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "zhangfei.gao@...mail.com" <zhangfei.gao@...mail.com>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        jean-philippe <jean-philippe@...aro.org>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        x86 <x86@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v4 05/11] iommu/sva: Assign a PASID to mm on PASID
 allocation and free it on mm exit

Hi, Zhangfei,

On Fri, Apr 15, 2022 at 07:52:03PM +0800, zhangfei.gao@...mail.com wrote:
> 
> 
> On 2022/4/15 下午6:50, Fenghua Yu wrote:
> > Hi, Zhangfei,
> > 
> > On Fri, Apr 15, 2022 at 06:14:09PM +0800, zhangfei.gao@...mail.com wrote:
> > I download this patch from:
> > https://lore.kernel.org/lkml/YllADL6uMoLllzQo@fyu1.sc.intel.com/raw
> > git am to either v5.18-rc2 or the latest upstream without any issue.
> It is my copy paste issue.
> 
> I have tested, nginx woks well.

Great!

> 
> Other than the following issue,
> Each time /sbin/nginx will alloc ioasid but not free.
> which I think it maybe nginx issue or the mis-usage, will ask there.

Which nginx/openssl function is supposed to call kernel sva_unbind? I couldn't
find the function in nginx tree.

If nginx doesn't free ioasid, it will cause ioasid leak and memory leak.

> 
> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>

Thank you for your testing!

> 
> > 
> > > It should work for arm.
> > > 
> > > In fact I have a similar patch at hand but pending since I found an issue.
> > > 
> > > I start & stop nginx via this cmd.
> > > //start
> > > sudo sbin/nginx                    // this alloc an ioasid=1
> > > //stop
> > > sudo sbin/nginx -s quit    // this does not free ioasid=1, but still alloc
> > > ioasid=2.
> > > So ioasid will keep allocated but not freed if continue start/stop nginx,
> > > though not impact the nginx function.
> > > 
> > > stop nginx with -s quit still calls
> > > src/core/nginx.c
> > > main -> ngx_ssl_init -> openssl engine:    bind_fn -> ... -> alloc asid
> > > But openssl engine: ENGINE_free is not called
> > > 
> > > Still in checking nginx code.
> > > 
> > > Or do you test with nginx?
> > On my X86 machine, nginx doesn't trigger the kernel sva binding function
> > to allocate ioasid. I tried pre- nstalled nginx/openssl and also tried my built
> > a few versions of nginx/openssl. nginx does call OPENSSL_init_ssl() but
> > doesn't go to the binding function. Don't know if it's my configuration issue.
> > Maybe you can give me some advice?
> I am using openssl engine, which use crypto driver and using sva via uacce.
> nginx -> openssl -> openssl engine -> sva related.

I'll do more nginx experiments.

> 
> > 
> > I test the patch with a few internal test tools and observe mmget()/mmput()
> > works fine in various cases.
> OK, thanks

Thank you very much!

-Fenghua