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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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 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next reply other threads:[~2024-04-07 21:32 UTC|newest] Thread overview: 22+ 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 0/2] RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE Christoph Müllner 2024-04-07 21:32 ` [PATCH v3 1/2] riscv: thead: Rename T-Head PBMT to MAE Christoph Müllner 2024-04-07 21:32 ` Christoph Müllner 2024-04-07 21:32 ` [PATCH v3 2/2] riscv: T-Head: Test availability bit before enabling MAE errata Christoph Müllner 2024-04-07 21:32 ` Christoph Müllner 2024-04-08 1:58 ` Yangyu Chen 2024-04-08 1:58 ` Yangyu Chen 2024-04-08 6:00 ` Christoph Müllner 2024-04-08 6:00 ` Christoph Müllner 2024-04-08 7:36 ` Yangyu Chen 2024-04-08 7:36 ` Yangyu Chen 2024-04-08 7:55 ` Christoph Müllner 2024-04-08 7:55 ` Christoph Müllner 2024-04-08 8:10 ` Conor Dooley 2024-04-08 8:10 ` Conor Dooley 2024-04-08 8:21 ` Yangyu Chen 2024-04-08 8:21 ` Yangyu Chen 2024-04-08 9:06 ` Conor Dooley 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 2024-04-25 23:00 ` patchwork-bot+linux-riscv
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