From 6179d4a213006491ff0d50073256f21fad22149b Mon Sep 17 00:00:00 2001 From: Christoph Müllner Date: Sun, 7 Apr 2024 23:32:35 +0200 Subject: riscv: thead: Rename T-Head PBMT to MAE MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit T-Head's vendor extension to set page attributes has the name MAE (memory attribute extension). Let's rename it, so it is clear what this referes to. Link: https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadmae.adoc Reviewed-by: Conor Dooley Signed-off-by: Christoph Müllner Link: https://lore.kernel.org/r/20240407213236.2121592-2-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt --- arch/riscv/errata/thead/errata.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'arch/riscv/errata') diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index b1c410bbc1ae..6e7ee1f16bee 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -19,10 +19,10 @@ #include #include -static bool errata_probe_pbmt(unsigned int stage, - unsigned long arch_id, unsigned long impid) +static bool errata_probe_mae(unsigned int stage, + unsigned long arch_id, unsigned long impid) { - if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PBMT)) + if (!IS_ENABLED(CONFIG_ERRATA_THEAD_MAE)) return false; if (arch_id != 0 || impid != 0) @@ -140,8 +140,8 @@ static u32 thead_errata_probe(unsigned int stage, { u32 cpu_req_errata = 0; - if (errata_probe_pbmt(stage, archid, impid)) - cpu_req_errata |= BIT(ERRATA_THEAD_PBMT); + if (errata_probe_mae(stage, archid, impid)) + cpu_req_errata |= BIT(ERRATA_THEAD_MAE); errata_probe_cmo(stage, archid, impid); -- cgit From 65b71cc35cc6631cb0a5b24f961fe64c085cb40b Mon Sep 17 00:00:00 2001 From: Christoph Müllner Date: Sun, 7 Apr 2024 23:32:36 +0200 Subject: riscv: T-Head: Test availability bit before enabling MAE errata MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit T-Head's memory attribute extension (XTheadMae) (non-compatible equivalent of RVI's Svpbmt) is currently assumed for all T-Head harts. However, QEMU recently decided to drop acceptance of guests that write reserved bits in PTEs. As XTheadMae uses reserved bits in PTEs and Linux applies the MAE errata for all T-Head harts, this broke the Linux startup on QEMU emulations of the C906 emulation. This patch attempts to address this issue by testing the MAE-enable bit in the th.sxstatus CSR. This CSR is available in HW and can be emulated in QEMU. This patch also makes the XTheadMae probing mechanism reliable, because a test for the right combination of mvendorid, marchid, and mimpid is not sufficient to enable MAE. Reviewed-by: Conor Dooley Signed-off-by: Christoph Müllner Link: https://lore.kernel.org/r/20240407213236.2121592-3-christoph.muellner@vrull.eu Signed-off-by: Palmer Dabbelt --- arch/riscv/errata/thead/errata.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'arch/riscv/errata') diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index 6e7ee1f16bee..bf6a0a6318ee 100644 --- a/arch/riscv/errata/thead/errata.c +++ b/arch/riscv/errata/thead/errata.c @@ -19,6 +19,9 @@ #include #include +#define CSR_TH_SXSTATUS 0x5c0 +#define SXSTATUS_MAEE _AC(0x200000, UL) + static bool errata_probe_mae(unsigned int stage, unsigned long arch_id, unsigned long impid) { @@ -28,11 +31,14 @@ static bool errata_probe_mae(unsigned int stage, if (arch_id != 0 || impid != 0) return false; - if (stage == RISCV_ALTERNATIVES_EARLY_BOOT || - stage == RISCV_ALTERNATIVES_MODULE) - return true; + if (stage != RISCV_ALTERNATIVES_EARLY_BOOT && + stage != RISCV_ALTERNATIVES_MODULE) + return false; - return false; + if (!(csr_read(CSR_TH_SXSTATUS) & SXSTATUS_MAEE)) + return false; + + return true; } /* -- cgit