From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: Re: powerpc/64s: Fix hypercall entry clobbering r12 input
Date: Fri, 21 Jul 2017 21:13:05 +1000 (AEST) [thread overview]
Message-ID: <3xDSmd6Xntz9t2H@ozlabs.org> (raw)
In-Reply-To: <20170718053244.7665-1-npiggin@gmail.com>
On Tue, 2017-07-18 at 05:32:44 UTC, Nicholas Piggin wrote:
> A previous optimisation incorrectly assumed the PAPR hcall does
> not use r12, and clobbers it upon entry. In fact it is used as
> an input. This can result in KVM guests crashing (observed with
> PR KVM).
>
> Instead of using r12 to save r13, tihs patch saves r13 in ctr.
> This is more costly, but not as slow as using the SPRG.
>
> Fixes: acd7d8cef0153 ("powerpc/64s: Optimize hypercall/syscall entry")
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/76fc0cfcc5b0f520062ca6d7225b22
cheers
prev parent reply other threads:[~2017-07-21 11:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-18 5:32 [PATCH] powerpc/64s: Fix hypercall entry clobbering r12 input Nicholas Piggin
2017-07-18 10:30 ` Michael Ellerman
2017-07-18 17:52 ` Ram Pai
2017-07-19 1:53 ` Nicholas Piggin
2017-07-21 11:13 ` Michael Ellerman [this message]
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