Re: [PATCH v4 4/4] target/riscv: add support for svpbmt extension

[Weiwei Li]

在 2022/1/17 下午3:18, Guo Ren 写道:

On Sun, Jan 16, 2022 at 11:08 AM Weiwei Li <liwei...@iscas.ac.cn> wrote:

- add PTE_PBMT bits: It uses two PTE bits, but otherwise has no effect on QEMU, 
since QEMU is sequentially consistent and doesn't model PMAs currently
- add PTE_PBMT bits check for inner PTE
- add reserved bits check for all PTE

Signed-off-by: Weiwei Li <liwei...@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqi...@iscas.ac.cn>
Tested-by: Heiko Stuebner <he...@sntech.de>
Reviewed-by: Anup Patel <a...@brainfault.org>
---
  target/riscv/cpu.c        | 1 +
  target/riscv/cpu.h        | 1 +
  target/riscv/cpu_bits.h   | 3 +++
  target/riscv/cpu_helper.c | 8 ++++++--
  4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 45ac98e06b..4f82bd00a3 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -670,6 +670,7 @@ static Property riscv_cpu_properties[] = {

      DEFINE_PROP_BOOL("svinval", RISCVCPU, cfg.ext_svinval, false),
      DEFINE_PROP_BOOL("svnapot", RISCVCPU, cfg.ext_svnapot, false),
+    DEFINE_PROP_BOOL("svpbmt", RISCVCPU, cfg.ext_svpbmt, false),

      DEFINE_PROP_BOOL("zba", RISCVCPU, cfg.ext_zba, true),
      DEFINE_PROP_BOOL("zbb", RISCVCPU, cfg.ext_zbb, true),
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index c3d1845ca1..53f314c752 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -329,6 +329,7 @@ struct RISCVCPU {
          bool ext_icsr;
          bool ext_svinval;
          bool ext_svnapot;
+        bool ext_svpbmt;
          bool ext_zfh;
          bool ext_zfhmin;

diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
index bc23e3b523..ee294c1d0b 100644
--- a/target/riscv/cpu_bits.h
+++ b/target/riscv/cpu_bits.h
@@ -486,7 +486,10 @@ typedef enum {
  #define PTE_A               0x040 /* Accessed */
  #define PTE_D               0x080 /* Dirty */
  #define PTE_SOFT            0x300 /* Reserved for Software */
+#define PTE_RSVD            0x1FC0000000000000 /* Reserved for future use */
+#define PTE_PBMT            0x6000000000000000 /* Page-based memory types */
  #define PTE_N               0x8000000000000000 /* NAPOT translation */
+#define PTE_ATTR            0xFFC0000000000000 /* All attributes bits */

  /* Page table PPN shift amount */
  #define PTE_PPN_SHIFT       10
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 832a2dd79c..f90766e026 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -619,17 +619,21 @@ restart:
              return TRANSLATE_FAIL;
          }

-        hwaddr ppn = (pte & ~(target_ulong)PTE_N) >> PTE_PPN_SHIFT;
+        hwaddr ppn = (pte & ~(target_ulong)PTE_ATTR) >> PTE_PPN_SHIFT;

This would break rv32. Please ref:
https://lore.kernel.org/qemu-devel/1569456861-8502-1-git-send-email-guo...@kernel.org/

Thanks for your comment . I'll merge this into our patchset.

Regards,

Weiwei Li

          RISCVCPU *cpu = env_archcpu(env);
          if (!cpu->cfg.ext_svnapot && (pte & PTE_N)) {
              return TRANSLATE_FAIL;
+        } else if (!cpu->cfg.ext_svpbmt && (pte & PTE_PBMT)) {
+            return TRANSLATE_FAIL;
+        } else if (pte & PTE_RSVD) {
+            return TRANSLATE_FAIL;
          } else if (!(pte & PTE_V)) {
              /* Invalid PTE */
              return TRANSLATE_FAIL;
          } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
              /* Inner PTE, continue walking */
-            if (pte & (PTE_D | PTE_A | PTE_U | PTE_N)) {
+            if (pte & (PTE_D | PTE_A | PTE_U | PTE_N | PTE_PBMT)) {
                  return TRANSLATE_FAIL;
              }
              base = ppn << PGSHIFT;
--
2.17.1