From: Qian Cai <qcai@redhat.com>
To: Daniel Axtens <dja@axtens.net>, linuxppc-dev@lists.ozlabs.org
Cc: cmr@informatik.wtf, spoorts2@in.ibm.com, npiggin@gmail.com
Subject: Re: [PATCH 3/7] powerpc/64s: flush L1D after user accesses
Date: Thu, 03 Dec 2020 13:50:35 -0500 [thread overview]
Message-ID: <da02e10d6b5a63dc10159d4420def15aa0bc4c19.camel@redhat.com> (raw)
In-Reply-To: <e82f315e08fe9f13ce4e94259968e0782ebb57a3.camel@redhat.com>
On Thu, 2020-12-03 at 12:17 -0500, Qian Cai wrote:
> []
> > +static inline bool
> > +bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
> > +{
> > + return WARN(mmu_has_feature(MMU_FTR_RADIX_KUAP) &&
> > + (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)),
> > + "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
> > +}
>
> A simple "echo t > /proc/sysrq-trigger" will trigger this warning almost
> endlessly on POWER9 NV.
I have just realized the patch just moved this warning around, so the issue was
pre-existent. Since I have not tested sysrq-t regularly, I am not sure when it
started to break. So far, I have reverted some of those for testing which did
not help, i.e., the sysrq-t issue remains.
16852975f0f Revert "powerpc/64s: Use early_mmu_has_feature() in set_kuap()"
129e240ead32 Revert "powerpc: Implement user_access_save() and user_access_restore()"
edb0046c842c Revert "powerpc/64s/kuap: Add missing isync to KUAP restore paths"
2d46ee87ce44 Revert "powerpc/64/kuap: Conditionally restore AMR in interrupt exit"
c1e0e805fc57 Revert "powerpc/64s/kuap: Conditionally restore AMR in kuap_restore_amr asm"
7f30b7aaf23a Revert "selftests/powerpc: rfi_flush: disable entry flush if present"
bc9b9967a100 Revert "powerpc/64s: flush L1D on kernel entry"
b77e7b54f5eb Revert "powerpc/64s: flush L1D after user accesses"
22dddf532c64 Revert "powerpc: Only include kup-radix.h for 64-bit Book3S"
2679d155c46a Revert "selftests/powerpc: entry flush test"
87954b9b4243 Revert "selftests/powerpc: refactor entry and rfi_flush tests"
342d82bd4c5d Revert "powerpc/64s: rename pnv|pseries_setup_rfi_flush to _setup_security_mitigations"
next prev parent reply other threads:[~2020-12-03 21:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 23:13 [PATCH 0/7] CVE-2020-4788: Speculation on incompletely validated data on IBM Power9 Daniel Axtens
2020-11-19 23:13 ` [PATCH 1/7] selftests/powerpc: rfi_flush: disable entry flush if present Daniel Axtens
2020-11-19 23:13 ` [PATCH 2/7] powerpc/64s: flush L1D on kernel entry Daniel Axtens
2020-11-19 23:13 ` [PATCH 3/7] powerpc/64s: flush L1D after user accesses Daniel Axtens
2020-12-03 17:17 ` Qian Cai
2020-12-03 17:31 ` Qian Cai
2020-12-03 18:50 ` Qian Cai [this message]
2020-12-04 6:21 ` Christophe Leroy
2020-11-19 23:13 ` [PATCH 4/7] powerpc: Only include kup-radix.h for 64-bit Book3S Daniel Axtens
2020-11-19 23:13 ` [PATCH 5/7] selftests/powerpc: entry flush test Daniel Axtens
2020-11-19 23:13 ` [PATCH 6/7] selftests/powerpc: refactor entry and rfi_flush tests Daniel Axtens
2020-11-19 23:13 ` [PATCH 7/7] powerpc/64s: rename pnv|pseries_setup_rfi_flush to _setup_security_mitigations Daniel Axtens
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