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/Kconfig.errata | 8 ++++---- arch/riscv/errata/thead/errata.c | 10 +++++----- arch/riscv/include/asm/errata_list.h | 20 ++++++++++---------- 3 files changed, 19 insertions(+), 19 deletions(-) diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata index 910ba8837add86..2acc7d876e1fb6 100644 --- a/arch/riscv/Kconfig.errata +++ b/arch/riscv/Kconfig.errata @@ -82,14 +82,14 @@ config ERRATA_THEAD Otherwise, please say "N" here to avoid unnecessary overhead. -config ERRATA_THEAD_PBMT - bool "Apply T-Head memory type errata" +config ERRATA_THEAD_MAE + bool "Apply T-Head's memory attribute extension (XTheadMae) errata" depends on ERRATA_THEAD && 64BIT && MMU select RISCV_ALTERNATIVE_EARLY default y help - This will apply the memory type errata to handle the non-standard - memory type bits in page-table-entries on T-Head SoCs. + This will apply the memory attribute extension errata to handle the + non-standard PTE utilization on T-Head SoCs (XTheadMae). If you don't know what to do here, say "Y". diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index b1c410bbc1aece..6e7ee1f16bee3e 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); diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h index ea33288f8a25b4..9bad9dfa2f7a16 100644 --- a/arch/riscv/include/asm/errata_list.h +++ b/arch/riscv/include/asm/errata_list.h @@ -23,7 +23,7 @@ #endif #ifdef CONFIG_ERRATA_THEAD -#define ERRATA_THEAD_PBMT 0 +#define ERRATA_THEAD_MAE 0 #define ERRATA_THEAD_PMU 1 #define ERRATA_THEAD_NUMBER 2 #endif @@ -53,20 +53,20 @@ asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID, \ * in the default case. */ #define ALT_SVPBMT_SHIFT 61 -#define ALT_THEAD_PBMT_SHIFT 59 +#define ALT_THEAD_MAE_SHIFT 59 #define ALT_SVPBMT(_val, prot) \ asm(ALTERNATIVE_2("li %0, 0\t\nnop", \ "li %0, %1\t\nslli %0,%0,%3", 0, \ RISCV_ISA_EXT_SVPBMT, CONFIG_RISCV_ISA_SVPBMT, \ "li %0, %2\t\nslli %0,%0,%4", THEAD_VENDOR_ID, \ - ERRATA_THEAD_PBMT, CONFIG_ERRATA_THEAD_PBMT) \ + ERRATA_THEAD_MAE, CONFIG_ERRATA_THEAD_MAE) \ : "=r"(_val) \ : "I"(prot##_SVPBMT >> ALT_SVPBMT_SHIFT), \ - "I"(prot##_THEAD >> ALT_THEAD_PBMT_SHIFT), \ + "I"(prot##_THEAD >> ALT_THEAD_MAE_SHIFT), \ "I"(ALT_SVPBMT_SHIFT), \ - "I"(ALT_THEAD_PBMT_SHIFT)) + "I"(ALT_THEAD_MAE_SHIFT)) -#ifdef CONFIG_ERRATA_THEAD_PBMT +#ifdef CONFIG_ERRATA_THEAD_MAE /* * IO/NOCACHE memory types are handled together with svpbmt, * so on T-Head chips, check if no other memory type is set, @@ -83,11 +83,11 @@ asm volatile(ALTERNATIVE( \ "slli t3, t3, %3\n\t" \ "or %0, %0, t3\n\t" \ "2:", THEAD_VENDOR_ID, \ - ERRATA_THEAD_PBMT, CONFIG_ERRATA_THEAD_PBMT) \ + ERRATA_THEAD_MAE, CONFIG_ERRATA_THEAD_MAE) \ : "+r"(_val) \ - : "I"(_PAGE_MTMASK_THEAD >> ALT_THEAD_PBMT_SHIFT), \ - "I"(_PAGE_PMA_THEAD >> ALT_THEAD_PBMT_SHIFT), \ - "I"(ALT_THEAD_PBMT_SHIFT) \ + : "I"(_PAGE_MTMASK_THEAD >> ALT_THEAD_MAE_SHIFT), \ + "I"(_PAGE_PMA_THEAD >> ALT_THEAD_MAE_SHIFT), \ + "I"(ALT_THEAD_MAE_SHIFT) \ : "t3") #else #define ALT_THEAD_PMA(_val) -- cgit 1.2.3-korg 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(-) diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c index 6e7ee1f16bee3e..bf6a0a6318ee30 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 1.2.3-korg