[PULL 2/3] target/loongarch: Fix tlb huge page loading issue

[Song Gao]

From: Xianglai Li <lixianglai@loongson.cn>

When we use qemu tcg simulation, the page size of bios is 4KB.
When using the level 2 super huge page (page size is 1G) to create the page 
table,
it is found that the content of the corresponding address space is abnormal,
resulting in the bios can not start the operating system and graphical 
interface normally.

The lddir and ldpte instruction emulation has
a problem with the use of super huge page processing above level 2.
The page size is not correctly calculated,
resulting in the wrong page size of the table entry found by tlb.

Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20240318070332.1273939-1-lixianglai@loongson.cn>
---
 target/loongarch/cpu-csr.h        |   3 +
 target/loongarch/internals.h      |   5 --
 target/loongarch/tcg/tlb_helper.c | 113 +++++++++++++++++++++---------
 3 files changed, 82 insertions(+), 39 deletions(-)

diff --git a/target/loongarch/cpu-csr.h b/target/loongarch/cpu-csr.h
index c59d7a9fcb..0834e91f30 100644
--- a/target/loongarch/cpu-csr.h
+++ b/target/loongarch/cpu-csr.h
@@ -67,6 +67,9 @@ FIELD(TLBENTRY, D, 1, 1)
 FIELD(TLBENTRY, PLV, 2, 2)
 FIELD(TLBENTRY, MAT, 4, 2)
 FIELD(TLBENTRY, G, 6, 1)
+FIELD(TLBENTRY, HUGE, 6, 1)
+FIELD(TLBENTRY, HGLOBAL, 12, 1)
+FIELD(TLBENTRY, LEVEL, 13, 2)
 FIELD(TLBENTRY_32, PPN, 8, 24)
 FIELD(TLBENTRY_64, PPN, 12, 36)
 FIELD(TLBENTRY_64, NR, 61, 1)
diff --git a/target/loongarch/internals.h b/target/loongarch/internals.h
index a2fc54c8a7..944153b180 100644
--- a/target/loongarch/internals.h
+++ b/target/loongarch/internals.h
@@ -16,11 +16,6 @@
 #define TARGET_PHYS_MASK MAKE_64BIT_MASK(0, TARGET_PHYS_ADDR_SPACE_BITS)
 #define TARGET_VIRT_MASK MAKE_64BIT_MASK(0, TARGET_VIRT_ADDR_SPACE_BITS)
 
-/* Global bit used for lddir/ldpte */
-#define LOONGARCH_PAGE_HUGE_SHIFT   6
-/* Global bit for huge page */
-#define LOONGARCH_HGLOBAL_SHIFT     12
-
 void loongarch_translate_init(void);
 
 void loongarch_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
diff --git a/target/loongarch/tcg/tlb_helper.c 
b/target/loongarch/tcg/tlb_helper.c
index 22be031ac7..57f5308632 100644
--- a/target/loongarch/tcg/tlb_helper.c
+++ b/target/loongarch/tcg/tlb_helper.c
@@ -17,6 +17,34 @@
 #include "exec/log.h"
 #include "cpu-csr.h"
 
+static void get_dir_base_width(CPULoongArchState *env, uint64_t *dir_base,
+                               uint64_t *dir_width, target_ulong level)
+{
+    switch (level) {
+    case 1:
+        *dir_base = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR1_BASE);
+        *dir_width = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR1_WIDTH);
+        break;
+    case 2:
+        *dir_base = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR2_BASE);
+        *dir_width = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR2_WIDTH);
+        break;
+    case 3:
+        *dir_base = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR3_BASE);
+        *dir_width = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR3_WIDTH);
+        break;
+    case 4:
+        *dir_base = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR4_BASE);
+        *dir_width = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR4_WIDTH);
+        break;
+    default:
+        /* level may be zero for ldpte */
+        *dir_base = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, PTBASE);
+        *dir_width = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, PTWIDTH);
+        break;
+    }
+}
+
 static void raise_mmu_exception(CPULoongArchState *env, target_ulong address,
                                 MMUAccessType access_type, int tlb_error)
 {
@@ -485,7 +513,25 @@ target_ulong helper_lddir(CPULoongArchState *env, 
target_ulong base,
     target_ulong badvaddr, index, phys, ret;
     int shift;
     uint64_t dir_base, dir_width;
-    bool huge = (base >> LOONGARCH_PAGE_HUGE_SHIFT) & 0x1;
+
+    if (unlikely((level == 0) || (level > 4))) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "Attepted LDDIR with level %"PRId64"\n", level);
+        return base;
+    }
+
+    if (FIELD_EX64(base, TLBENTRY, HUGE)) {
+        if (unlikely(level == 4)) {
+            qemu_log_mask(LOG_GUEST_ERROR,
+                          "Attempted use of level 4 huge page\n");
+        }
+
+        if (FIELD_EX64(base, TLBENTRY, LEVEL)) {
+            return base;
+        } else {
+            return FIELD_DP64(base, TLBENTRY, LEVEL, level);
+        }
+    }
 
     badvaddr = env->CSR_TLBRBADV;
     base = base & TARGET_PHYS_MASK;
@@ -494,30 +540,7 @@ target_ulong helper_lddir(CPULoongArchState *env, 
target_ulong base,
     shift = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, PTEWIDTH);
     shift = (shift + 1) * 3;
 
-    if (huge) {
-        return base;
-    }
-    switch (level) {
-    case 1:
-        dir_base = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR1_BASE);
-        dir_width = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR1_WIDTH);
-        break;
-    case 2:
-        dir_base = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR2_BASE);
-        dir_width = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, DIR2_WIDTH);
-        break;
-    case 3:
-        dir_base = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR3_BASE);
-        dir_width = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR3_WIDTH);
-        break;
-    case 4:
-        dir_base = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR4_BASE);
-        dir_width = FIELD_EX64(env->CSR_PWCH, CSR_PWCH, DIR4_WIDTH);
-        break;
-    default:
-        do_raise_exception(env, EXCCODE_INE, GETPC());
-        return 0;
-    }
+    get_dir_base_width(env, &dir_base, &dir_width, level);
     index = (badvaddr >> dir_base) & ((1 << dir_width) - 1);
     phys = base | index << shift;
     ret = ldq_phys(cs->as, phys) & TARGET_PHYS_MASK;
@@ -530,20 +553,42 @@ void helper_ldpte(CPULoongArchState *env, target_ulong 
base, target_ulong odd,
     CPUState *cs = env_cpu(env);
     target_ulong phys, tmp0, ptindex, ptoffset0, ptoffset1, ps, badv;
     int shift;
-    bool huge = (base >> LOONGARCH_PAGE_HUGE_SHIFT) & 0x1;
     uint64_t ptbase = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, PTBASE);
     uint64_t ptwidth = FIELD_EX64(env->CSR_PWCL, CSR_PWCL, PTWIDTH);
+    uint64_t dir_base, dir_width;
 
+    /*
+     * The parameter "base" has only two types,
+     * one is the page table base address,
+     * whose bit 6 should be 0,
+     * and the other is the huge page entry,
+     * whose bit 6 should be 1.
+     */
     base = base & TARGET_PHYS_MASK;
+    if (FIELD_EX64(base, TLBENTRY, HUGE)) {
+        /*
+         * Gets the huge page level and Gets huge page size.
+         * Clears the huge page level information in the entry.
+         * Clears huge page bit.
+         * Move HGLOBAL bit to GLOBAL bit.
+         */
+        get_dir_base_width(env, &dir_base, &dir_width,
+                           FIELD_EX64(base, TLBENTRY, LEVEL));
+
+        base = FIELD_DP64(base, TLBENTRY, LEVEL, 0);
+        base = FIELD_DP64(base, TLBENTRY, HUGE, 0);
+        if (FIELD_EX64(base, TLBENTRY, HGLOBAL)) {
+            base = FIELD_DP64(base, TLBENTRY, HGLOBAL, 0);
+            base = FIELD_DP64(base, TLBENTRY, G, 1);
+        }
 
-    if (huge) {
-        /* Huge Page. base is paddr */
-        tmp0 = base ^ (1 << LOONGARCH_PAGE_HUGE_SHIFT);
-        /* Move Global bit */
-        tmp0 = ((tmp0 & (1 << LOONGARCH_HGLOBAL_SHIFT))  >>
-                LOONGARCH_HGLOBAL_SHIFT) << R_TLBENTRY_G_SHIFT |
-                (tmp0 & (~(1 << LOONGARCH_HGLOBAL_SHIFT)));
-        ps = ptbase + ptwidth - 1;
+        ps = dir_base + dir_width - 1;
+        /*
+         * Huge pages are evenly split into parity pages
+         * when loaded into the tlb,
+         * so the tlb page size needs to be divided by 2.
+         */
+        tmp0 = base;
         if (odd) {
             tmp0 += MAKE_64BIT_MASK(ps, 1);
         }
-- 
2.25.1