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-rw-r--r--cputlb.c120
-rw-r--r--include/exec/cputlb.h2
2 files changed, 95 insertions, 27 deletions
diff --git a/cputlb.c b/cputlb.c
index c50254b..6500335 100644
--- a/cputlb.c
+++ b/cputlb.c
@@ -342,32 +342,90 @@ void tlb_unprotect_code(ram_addr_t ram_addr)
cpu_physical_memory_set_dirty_flag(ram_addr, DIRTY_MEMORY_CODE);
}
-static bool tlb_is_dirty_ram(CPUTLBEntry *tlbe)
-{
- return (tlbe->addr_write & (TLB_INVALID_MASK|TLB_MMIO|TLB_NOTDIRTY)) == 0;
-}
-void tlb_reset_dirty_range(CPUTLBEntry *tlb_entry, uintptr_t start,
+/*
+ * Dirty write flag handling
+ *
+ * When the TCG code writes to a location it looks up the address in
+ * the TLB and uses that data to compute the final address. If any of
+ * the lower bits of the address are set then the slow path is forced.
+ * There are a number of reasons to do this but for normal RAM the
+ * most usual is detecting writes to code regions which may invalidate
+ * generated code.
+ *
+ * Because we want other vCPUs to respond to changes straight away we
+ * update the te->addr_write field atomically. If the TLB entry has
+ * been changed by the vCPU in the mean time we skip the update.
+ *
+ * As this function uses atomic accesses we also need to ensure
+ * updates to tlb_entries follow the same access rules. We don't need
+ * to worry about this for oversized guests as MTTCG is disabled for
+ * them.
+ */
+
+static void tlb_reset_dirty_range(CPUTLBEntry *tlb_entry, uintptr_t start,
uintptr_t length)
{
- uintptr_t addr;
+#if TCG_OVERSIZED_GUEST
+ uintptr_t addr = tlb_entry->addr_write;
- if (tlb_is_dirty_ram(tlb_entry)) {
- addr = (tlb_entry->addr_write & TARGET_PAGE_MASK) + tlb_entry->addend;
+ if ((addr & (TLB_INVALID_MASK | TLB_MMIO | TLB_NOTDIRTY)) == 0) {
+ addr &= TARGET_PAGE_MASK;
+ addr += tlb_entry->addend;
if ((addr - start) < length) {
tlb_entry->addr_write |= TLB_NOTDIRTY;
}
}
+#else
+ /* paired with atomic_mb_set in tlb_set_page_with_attrs */
+ uintptr_t orig_addr = atomic_mb_read(&tlb_entry->addr_write);
+ uintptr_t addr = orig_addr;
+
+ if ((addr & (TLB_INVALID_MASK | TLB_MMIO | TLB_NOTDIRTY)) == 0) {
+ addr &= TARGET_PAGE_MASK;
+ addr += atomic_read(&tlb_entry->addend);
+ if ((addr - start) < length) {
+ uintptr_t notdirty_addr = orig_addr | TLB_NOTDIRTY;
+ atomic_cmpxchg(&tlb_entry->addr_write, orig_addr, notdirty_addr);
+ }
+ }
+#endif
+}
+
+/* For atomic correctness when running MTTCG we need to use the right
+ * primitives when copying entries */
+static inline void copy_tlb_helper(CPUTLBEntry *d, CPUTLBEntry *s,
+ bool atomic_set)
+{
+#if TCG_OVERSIZED_GUEST
+ *d = *s;
+#else
+ if (atomic_set) {
+ d->addr_read = s->addr_read;
+ d->addr_code = s->addr_code;
+ atomic_set(&d->addend, atomic_read(&s->addend));
+ /* Pairs with flag setting in tlb_reset_dirty_range */
+ atomic_mb_set(&d->addr_write, atomic_read(&s->addr_write));
+ } else {
+ d->addr_read = s->addr_read;
+ d->addr_write = atomic_read(&s->addr_write);
+ d->addr_code = s->addr_code;
+ d->addend = atomic_read(&s->addend);
+ }
+#endif
}
+/* This is a cross vCPU call (i.e. another vCPU resetting the flags of
+ * the target vCPU). As such care needs to be taken that we don't
+ * dangerously race with another vCPU update. The only thing actually
+ * updated is the target TLB entry ->addr_write flags.
+ */
void tlb_reset_dirty(CPUState *cpu, ram_addr_t start1, ram_addr_t length)
{
CPUArchState *env;
int mmu_idx;
- assert_cpu_is_self(cpu);
-
env = cpu->env_ptr;
for (mmu_idx = 0; mmu_idx < NB_MMU_MODES; mmu_idx++) {
unsigned int i;
@@ -455,7 +513,7 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
target_ulong address;
target_ulong code_address;
uintptr_t addend;
- CPUTLBEntry *te;
+ CPUTLBEntry *te, *tv, tn;
hwaddr iotlb, xlat, sz;
unsigned vidx = env->vtlb_index++ % CPU_VTLB_SIZE;
int asidx = cpu_asidx_from_attrs(cpu, attrs);
@@ -490,41 +548,50 @@ void tlb_set_page_with_attrs(CPUState *cpu, target_ulong vaddr,
index = (vaddr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
te = &env->tlb_table[mmu_idx][index];
-
/* do not discard the translation in te, evict it into a victim tlb */
- env->tlb_v_table[mmu_idx][vidx] = *te;
+ tv = &env->tlb_v_table[mmu_idx][vidx];
+
+ /* addr_write can race with tlb_reset_dirty_range */
+ copy_tlb_helper(tv, te, true);
+
env->iotlb_v[mmu_idx][vidx] = env->iotlb[mmu_idx][index];
/* refill the tlb */
env->iotlb[mmu_idx][index].addr = iotlb - vaddr;
env->iotlb[mmu_idx][index].attrs = attrs;
- te->addend = addend - vaddr;
+
+ /* Now calculate the new entry */
+ tn.addend = addend - vaddr;
if (prot & PAGE_READ) {
- te->addr_read = address;
+ tn.addr_read = address;
} else {
- te->addr_read = -1;
+ tn.addr_read = -1;
}
if (prot & PAGE_EXEC) {
- te->addr_code = code_address;
+ tn.addr_code = code_address;
} else {
- te->addr_code = -1;
+ tn.addr_code = -1;
}
+
+ tn.addr_write = -1;
if (prot & PAGE_WRITE) {
if ((memory_region_is_ram(section->mr) && section->readonly)
|| memory_region_is_romd(section->mr)) {
/* Write access calls the I/O callback. */
- te->addr_write = address | TLB_MMIO;
+ tn.addr_write = address | TLB_MMIO;
} else if (memory_region_is_ram(section->mr)
&& cpu_physical_memory_is_clean(
memory_region_get_ram_addr(section->mr) + xlat)) {
- te->addr_write = address | TLB_NOTDIRTY;
+ tn.addr_write = address | TLB_NOTDIRTY;
} else {
- te->addr_write = address;
+ tn.addr_write = address;
}
- } else {
- te->addr_write = -1;
}
+
+ /* Pairs with flag setting in tlb_reset_dirty_range */
+ copy_tlb_helper(te, &tn, true);
+ /* atomic_mb_set(&te->addr_write, write_address); */
}
/* Add a new TLB entry, but without specifying the memory
@@ -687,10 +754,13 @@ static bool victim_tlb_hit(CPUArchState *env, size_t mmu_idx, size_t index,
if (cmp == page) {
/* Found entry in victim tlb, swap tlb and iotlb. */
CPUTLBEntry tmptlb, *tlb = &env->tlb_table[mmu_idx][index];
+
+ copy_tlb_helper(&tmptlb, tlb, false);
+ copy_tlb_helper(tlb, vtlb, true);
+ copy_tlb_helper(vtlb, &tmptlb, true);
+
CPUIOTLBEntry tmpio, *io = &env->iotlb[mmu_idx][index];
CPUIOTLBEntry *vio = &env->iotlb_v[mmu_idx][vidx];
-
- tmptlb = *tlb; *tlb = *vtlb; *vtlb = tmptlb;
tmpio = *io; *io = *vio; *vio = tmpio;
return true;
}
diff --git a/include/exec/cputlb.h b/include/exec/cputlb.h
index d454c00..3f94178 100644
--- a/include/exec/cputlb.h
+++ b/include/exec/cputlb.h
@@ -23,8 +23,6 @@
/* cputlb.c */
void tlb_protect_code(ram_addr_t ram_addr);
void tlb_unprotect_code(ram_addr_t ram_addr);
-void tlb_reset_dirty_range(CPUTLBEntry *tlb_entry, uintptr_t start,
- uintptr_t length);
extern int tlb_flush_count;
#endif
generated by cgit v1.1 at 2024-12-26 14:50:23 +0000