diff options
| author | Palmer Dabbelt <palmer@rivosinc.com> | 2024-04-25 10:22:36 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-04-26 10:21:57 -0700 |
| commit | 6beb6bc5a81e1433a1534e75173f67d42a6f225a (patch) | |
| tree | 8a718f102f521d318f1d953df178525431006eeb /arch/riscv/include/asm | |
| parent | 49408400d683ae4f41e414dfcb615166cc93be5c (diff) | |
| parent | 65b71cc35cc6631cb0a5b24f961fe64c085cb40b (diff) | |
Merge patch series "RISC-V: Test th.sxstatus.MAEE bit before enabling MAEE"
Christoph Müllner <christoph.muellner@vrull.eu> says:
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").
* b4-shazam-lts:
riscv: T-Head: Test availability bit before enabling MAE errata
riscv: thead: Rename T-Head PBMT to MAE
Link: https://lore.kernel.org/r/20240407213236.2121592-1-christoph.muellner@vrull.eu
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include/asm')
| -rw-r--r-- | arch/riscv/include/asm/errata_list.h | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h index 1f2dbfb8a8bf..efd851e1b483 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) |