From: Marc Zyngier <maz@kernel.org>
To: Andrew Scull <ascull@google.com>
Cc: kernel-team@android.com, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH] arm64: kvm: Stop clobbering x0 for HVC_SOFT_RESTART
Date: Mon, 06 Jul 2020 11:11:15 +0100 [thread overview]
Message-ID: <a765085746f61ed8deff396fae1d89a1@kernel.org> (raw)
In-Reply-To: <20200706095259.1338221-1-ascull@google.com>
On 2020-07-06 10:52, Andrew Scull wrote:
> HVC_SOFT_RESTART is given values for x0-2 that it should installed
> before exiting to the new address so should not set x0 to stub HVC
> success or failure code.
>
> Signed-off-by: Andrew Scull <ascull@google.com>
> ---
> arch/arm64/kvm/hyp-init.S | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S
> index 6e6ed5581eed..e76c0e89d48e 100644
> --- a/arch/arm64/kvm/hyp-init.S
> +++ b/arch/arm64/kvm/hyp-init.S
> @@ -136,11 +136,15 @@ SYM_CODE_START(__kvm_handle_stub_hvc)
>
> 1: cmp x0, #HVC_RESET_VECTORS
> b.ne 1f
> -reset:
> +
> /*
> - * Reset kvm back to the hyp stub. Do not clobber x0-x4 in
> - * case we coming via HVC_SOFT_RESTART.
> + * Set the HVC_RESET_VECTORS return code before entering the common
> + * path so that we do not clobber x0-x2 in case we are coming via
> + * HVC_SOFT_RESTART.
> */
> + mov x0, xzr
> +reset:
> + /* Reset kvm back to the hyp stub. */
> mrs x5, sctlr_el2
> mov_q x6, SCTLR_ELx_FLAGS
> bic x5, x5, x6 // Clear SCTL_M and etc
> @@ -151,7 +155,6 @@ reset:
> /* Install stub vectors */
> adr_l x5, __hyp_stub_vectors
> msr vbar_el2, x5
> - mov x0, xzr
> eret
>
> 1: /* Bad stub call */
Huh, nice catch. I wonder what the fuss is about kexec, really,
given that it is *that* broken. This deserves:
Fixes: af42f20480bf1 ("arm64: hyp-stub: Zero x0 on successful stub
handling")
Cc: stable@vger.kernel.org
Thanks,
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2020-07-06 10:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 9:52 [PATCH] arm64: kvm: Stop clobbering x0 for HVC_SOFT_RESTART Andrew Scull
2020-07-06 10:11 ` Marc Zyngier [this message]
2020-07-08 16:22 ` James Morse
2020-07-06 10:29 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a765085746f61ed8deff396fae1d89a1@kernel.org \
--to=maz@kernel.org \
--cc=ascull@google.com \
--cc=kernel-team@android.com \
--cc=kvmarm@lists.cs.columbia.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).