linux-kernel - Re: SME/32-bit regression

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Date:   Wed, 6 Sep 2017 15:57:40 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
cc:     Borislav Petkov <bp@...en8.de>, thomas.lendacky@....com,
        X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: SME/32-bit regression

On Wed, 6 Sep 2017, Boris Ostrovsky wrote:
> On 09/06/2017 05:26 AM, Borislav Petkov wrote:
> > On Tue, Sep 05, 2017 at 11:45:07PM -0400, Boris Ostrovsky wrote:
> >> It appears there is a regression for 32-bit kernels due to SME changes.
> >>
> >> I bisected my particular problem
> > It being? Doesn't boot, splats?
> 
> Xen guest crashes very early, before a splat can can be generated.
> 
> >
> >> (Xen PV guest) to
> >> 21729f81ce8ae76a6995681d40e16f7ce8075db4 but I also saw pmd_clear_bad()
> >> errors on baremetal. This seems to be caused by sme_me_mask being an
> >> unsigned long as opposed to phys_addr_t (the actual problem is that
> >> __PHYSICAL_MASK is truncated). When I declare it as u64 and drop unsigned
> >> long cast in __sme_set()/__sme_clr() the problem goes way. (This presumably
> >> won't work for non-PAE which I haven't tried).
> > Right, so I think we should do this because those macros should not have
> > any effect on !CONFIG_AMD_MEM_ENCRYPT setups.
> 
> This won't help though if kernel is built with SME support.

Which is not the case for 32bit. SME depends on 64bit