Re: [PATCH v2 RESEND] tcg/loongarch: strip flag bits in lddir/ldpte address calculation

[Bibo Mao]

On 2026/9/21 下午12:17, SignKirigami wrote:
On 2026年9月20日星期日 中国标准时间 11:48:53，Bibo Mao wrote：

On 2026/9/20 上午10:42, SignKirigami wrote:
helper_lddir and helper_ldpte used TARGET_PHYS_MASK (bits 0-47) when
extracting the base address from a directory entry.  This retained flag
bits (V, D, PLV, MAT, etc.) at positions 0-11, which were then OR'd
For LoongArch, what is scenery with DIR/PTE entry where bit0-bit11 such
as (V, D, PLV, MAT, etc.) is used, except Huge bit?

Regards
Bibo Mao
This patch is originally from rcore developers, and it seems to be hardware's
responsibility to clear 0-11 bits.
Could you show me the web link how hardware clears 0-11 bits with 
LDDIR/LDPTE instruction?

Regards
Bibo Mao

Regards
SignKirigami
with the next-level index, producing a wrong physical address whenever
the directory entry carried non-zero flags.

Fix both helpers to extract only the PPN field (bits 12-47) before
computing the address of the next-level page table entry.

Signed-off-by: numpy1314 <xz...@mail.ustc.edu.cn>
Signed-off-by: SignKirigami <prc...@krgm.moe>
---
This patch is a resend of [1], Sorry for wrongly handling Signed-off-by.
   
[1]: https://lists.gnu.org/archive/html/qemu-devel/2026-09/msg05581.html.
   
   target/loongarch/tcg/tlb_helper.c | 7 ++-----
   1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/target/loongarch/tcg/tlb_helper.c 
b/target/loongarch/tcg/tlb_helper.c
index 40cc076424..529b22347d 100644
--- a/target/loongarch/tcg/tlb_helper.c
+++ b/target/loongarch/tcg/tlb_helper.c
@@ -750,7 +750,7 @@ target_ulong helper_lddir(CPULoongArchState *env, 
target_ulong base,
       }
   
       badvaddr = sys->CSR_TLBRBADV;
-    base = base & palen_mask;
+    base = base & palen_mask & ~MAKE_64BIT_MASK(0, 12);
       get_dir_base_width(env, &dir_base, &dir_width, level);
       index = (badvaddr >> dir_base) & ((1 << dir_width) - 1);
       phys = base | index << 3;
@@ -773,7 +773,6 @@ void helper_ldpte(CPULoongArchState *env, target_ulong 
base, target_ulong odd,
       uint64_t dir_base, dir_width;
       uint8_t  ps;
   
-
       /*
        * The parameter "base" has only two types,
        * one is the page table base address,
@@ -815,9 +814,7 @@ void helper_ldpte(CPULoongArchState *env, target_ulong 
base, target_ulong odd,
           }
       } else {
           badv = sys->CSR_TLBRBADV;
-
-        base = base & palen_mask;
-
+        base = base & palen_mask & ~MAKE_64BIT_MASK(0, 12);
           ptindex = (badv >> ptbase) & ((1 << ptwidth) - 1);
           ptindex = ptindex & ~0x1;   /* clear bit 0 */
           ptoffset0 = ptindex << 3;