From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Date: Fri, 17 Jan 2020 03:43:54 +0000 Subject: Re: [PATCH v3] powerpc/mm: Remove kvm radix prefetch workaround for Power9 DD2.2 Message-Id: <20200117034354.GA31793@blackberry> List-Id: References: <20191206031722.25781-1-jniethe5@gmail.com> In-Reply-To: <20191206031722.25781-1-jniethe5@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jordan Niethe Cc: oohall@gmail.com, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org On Fri, Dec 06, 2019 at 02:17:22PM +1100, Jordan Niethe wrote: > Commit a25bd72badfa ("powerpc/mm/radix: Workaround prefetch issue with > KVM") introduced a number of workarounds as coming out of a guest with > the mmu enabled would make the cpu would start running in hypervisor > state with the PID value from the guest. The cpu will then start > prefetching for the hypervisor with that PID value. > > In Power9 DD2.2 the cpu behaviour was modified to fix this. When > accessing Quadrant 0 in hypervisor mode with LPID != 0 prefetching will > not be performed. This means that we can get rid of the workarounds for > Power9 DD2.2 and later revisions. Add a new cpu feature > CPU_FTR_P9_RADIX_PREFETCH_BUG to indicate if the workarounds are needed. > > Signed-off-by: Jordan Niethe Acked-by: Paul Mackerras