From: "Christoph Müllner" <christoph.muellner@vrull.eu>
To: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Philipp Tomsich" <philipp.tomsich@vrull.eu>,
"Björn Töpel" <bjorn@kernel.org>,
"Daniel Henrique Barboza" <dbarboza@ventanamicro.com>,
"Heiko Stuebner" <heiko@sntech.de>,
"Cooper Qu" <cooper.qu@linux.alibaba.com>,
"Zhiwei Liu" <zhiwei_liu@linux.alibaba.com>,
"Huang Tao" <eric.huang@linux.alibaba.com>,
"Alistair Francis" <alistair.francis@wdc.com>,
"Andrew Jones" <ajones@ventanamicro.com>,
"Conor Dooley" <conor@kernel.org>,
"Qingfang Deng" <dqfext@gmail.com>,
"Alexandre Ghiti" <alex@ghiti.fr>,
"Samuel Holland" <samuel.holland@sifive.com>
Cc: "Christoph Müllner" <christoph.muellner@vrull.eu>
Subject: [PATCH v3 0/2] RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE
Date: Sun, 7 Apr 2024 23:32:34 +0200 [thread overview]
Message-ID: <20240407213236.2121592-1-christoph.muellner@vrull.eu> (raw)
Currently, the Linux kernel suffers from a boot regression when running
on the c906 QEMU emulation. Details have been reported here by Björn Töpel:
https://lists.gnu.org/archive/html/qemu-devel/2024-01/msg04766.html
The main issue is, that Linux enables XTheadMae for CPUs that have a T-Head
mvendorid but QEMU maintainers don't want to emulate a CPU that uses
reserved bits in PTEs. See also the following discussion for more
context:
https://lists.gnu.org/archive/html/qemu-devel/2024-02/msg00775.html
This series renames "T-Head PBMT" to "MAE"/"XTheadMae" and only enables
it if the th.sxstatus.MAEE bit is set.
The th.sxstatus CSR is documented here:
https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadsxstatus.adoc
XTheadMae is documented here:
https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc
The QEMU patch to emulate th.sxstatus with the MAEE bit not set is here:
https://lore.kernel.org/all/20240329120427.684677-1-christoph.muellner@vrull.eu/
After applying the referenced QEMU patch, this patchset allows to
successfully boot a C906 QEMU system emulation ("-cpu thead-c906").
Changes in v3:
* Rename to MAE instead of MAEE
Changes in v2:
* use th.sxstatus.MAEE instead of th.mxstatus.MAEE
Christoph Müllner (2):
riscv: thead: Rename T-Head PBMT to MAE
riscv: T-Head: Test availability bit before enabling MAE errata
arch/riscv/Kconfig.errata | 8 ++++----
arch/riscv/errata/thead/errata.c | 24 +++++++++++++++---------
arch/riscv/include/asm/errata_list.h | 20 ++++++++++----------
3 files changed, 29 insertions(+), 23 deletions(-)
--
2.44.0
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next reply other threads:[~2024-04-07 21:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-07 21:32 Christoph Müllner [this message]
2024-04-07 21:32 ` [PATCH v3 1/2] riscv: thead: Rename T-Head PBMT to MAE Christoph Müllner
2024-04-07 21:32 ` [PATCH v3 2/2] riscv: T-Head: Test availability bit before enabling MAE errata Christoph Müllner
2024-04-08 1:58 ` Yangyu Chen
2024-04-08 6:00 ` Christoph Müllner
2024-04-08 7:36 ` Yangyu Chen
2024-04-08 7:55 ` Christoph Müllner
2024-04-08 8:10 ` Conor Dooley
2024-04-08 8:21 ` Yangyu Chen
2024-04-08 9:06 ` Conor Dooley
2024-04-25 23:00 ` [PATCH v3 0/2] RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE patchwork-bot+linux-riscv
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