Re: [PATCH v4 4/7] Convert 'info tlb' to use generic iterator.

["Dr. David Alan Gilbert" <dave@treblig.org>]

* Don Porter (porter@cs.unc.edu) wrote:
> If the the guest is using nested page tables, change the output format
> slightly, to first show guest virtual to guest physical, then guest
> physical to host physical, as below:

This surprises me from the title; the title made me think
this was a change purely to the implementation.

> (qemu) info tlb
> Info guest TLB (guest virtual to guest physical):

It's a shame that the code that prints this has no way to know the column widths,
since it would be nice to have:

   guest virt           guest phys    ???????????
> 0000008000800000: 000000000076a000  -------U-P
> 0000008000801000: 000000000076b000  -------U-P
> 0000008000802000: 000000000076c000  -------U-P
> 0000008000803000: 000000000076d000  -------U-P
> [...]
> 0000008004ffd000: 0000000000ffd000  --------WP
> 0000008004ffe000: 0000000000ffe000  --------WP
> 0000008004fff000: 0000000000fff000  --------WP

> Info host TLB, (guest physical to host physical):

Do you actually want this to happen in the same operation, or do you
want info tlb -h (e.g.) to get the host info?

> 0000000000001000: 0000000001b20000  ----XWR
> 0000000000002000: 0000000001b21000  ----XWR
> 0000000000003000: 0000000001b22000  ----XWR
> 0000000000004000: 0000000001b23000  ----XWR
> 0000000000005000: 0000000001b24000  ----XWR
> [...]
> 
> Signed-off-by: Don Porter <porter@cs.unc.edu>
> ---
>  include/hw/core/sysemu-cpu-ops.h |   7 +
>  target/i386/cpu.c                |   1 +
>  target/i386/cpu.h                |   2 +
>  target/i386/monitor.c            | 233 +++++++++----------------------
>  4 files changed, 75 insertions(+), 168 deletions(-)
> 
> diff --git a/include/hw/core/sysemu-cpu-ops.h b/include/hw/core/sysemu-cpu-ops.h
> index d0e939def8..083df4717c 100644
> --- a/include/hw/core/sysemu-cpu-ops.h
> +++ b/include/hw/core/sysemu-cpu-ops.h
> @@ -225,6 +225,13 @@ typedef struct SysemuCPUOps {
>      bool (*mon_flush_page_print_state)(CPUState *cs,
>                                         struct mem_print_state *state);
>  
> +    /**
> +     * @mon_print_pte: Hook called by the monitor to print a page
> +     * table entry at address addr, with contents pte.
> +     */
> +    void (*mon_print_pte) (CPUState *cs, GString *buf, hwaddr addr,
> +                           hwaddr pte, uint64_t prot, int mmu_idx);
> +
>  } SysemuCPUOps;
>  
>  int compressing_iterator(CPUState *cs, void *data, DecodedPTE *pte,
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index ec419e0ef0..030198497a 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -8388,6 +8388,7 @@ static const struct SysemuCPUOps i386_sysemu_ops = {
>      .mon_init_page_table_iterator = &x86_mon_init_page_table_iterator,
>      .mon_info_pg_print_header = &x86_mon_info_pg_print_header,
>      .mon_flush_page_print_state = &x86_mon_flush_print_pg_state,
> +    .mon_print_pte = &x86_mon_print_pte,
>  };
>  #endif
>  
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 4e5877f41d..413c743c1a 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -2264,6 +2264,8 @@ bool x86_mon_init_page_table_iterator(CPUState *cpu, GString *buf, int mmu_idx,
>                                        struct mem_print_state *state);
>  void x86_mon_info_pg_print_header(struct mem_print_state *state);
>  bool x86_mon_flush_print_pg_state(CPUState *cs, struct mem_print_state *state);
> +void x86_mon_print_pte(CPUState *cs, GString *out_buf, hwaddr addr,
> +                       hwaddr child, uint64_t prot, int mmu_idx);
>  bool x86_ptw_translate(CPUState *cs, vaddr vaddress, hwaddr *hpa,
>                         bool debug, int mmu_idx, bool user_access,
>                         const MMUAccessType access_type, uint64_t *page_size,
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c
> index 8ef92e7c42..d88347684b 100644
> --- a/target/i386/monitor.c
> +++ b/target/i386/monitor.c
> @@ -224,201 +224,98 @@ static hwaddr addr_canonical(CPUArchState *env, hwaddr addr)
>      return addr;
>  }
>  
> -static void print_pte(Monitor *mon, CPUArchState *env, hwaddr addr,
> -                      hwaddr pte, hwaddr mask)
> +void x86_mon_print_pte(CPUState *cs, GString *out_buf, hwaddr addr,
> +                       hwaddr child, uint64_t prot, int mmu_idx)
>  {
> +    CPUX86State *env = cpu_env(cs);
> +    g_autoptr(GString) buf = g_string_new("");
> +
>      addr = addr_canonical(env, addr);
>  
> -    monitor_printf(mon, HWADDR_FMT_plx ": " HWADDR_FMT_plx
> -                   " %c%c%c%c%c%c%c%c%c\n",
> -                   addr,
> -                   pte & mask,
> -                   pte & PG_NX_MASK ? 'X' : '-',
> -                   pte & PG_GLOBAL_MASK ? 'G' : '-',
> -                   pte & PG_PSE_MASK ? 'P' : '-',
> -                   pte & PG_DIRTY_MASK ? 'D' : '-',
> -                   pte & PG_ACCESSED_MASK ? 'A' : '-',
> -                   pte & PG_PCD_MASK ? 'C' : '-',
> -                   pte & PG_PWT_MASK ? 'T' : '-',
> -                   pte & PG_USER_MASK ? 'U' : '-',
> -                   pte & PG_RW_MASK ? 'W' : '-');
> -}
> +    g_string_append_printf(buf, HWADDR_FMT_plx ": " HWADDR_FMT_plx " ",
> +                           addr, child);
>  
> -static void tlb_info_32(Monitor *mon, CPUArchState *env)
> -{
> -    unsigned int l1, l2;
> -    uint32_t pgd, pde, pte;
> +    g_string_append_printf(buf, " %s", pg_bits(cs, prot, mmu_idx));
>  
> -    pgd = env->cr[3] & ~0xfff;
> -    for(l1 = 0; l1 < 1024; l1++) {

It's nice to see all this hairy code disappearing.

> -        cpu_physical_memory_read(pgd + l1 * 4, &pde, 4);
> -        pde = le32_to_cpu(pde);
> -        if (pde & PG_PRESENT_MASK) {
> -            if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
> -                /* 4M pages */
> -                print_pte(mon, env, (l1 << 22), pde, ~((1 << 21) - 1));
> -            } else {
> -                for(l2 = 0; l2 < 1024; l2++) {
> -                    cpu_physical_memory_read((pde & ~0xfff) + l2 * 4, &pte, 4);
> -                    pte = le32_to_cpu(pte);
> -                    if (pte & PG_PRESENT_MASK) {
> -                        print_pte(mon, env, (l1 << 22) + (l2 << 12),
> -                                  pte & ~PG_PSE_MASK,
> -                                  ~0xfff);
> -                    }
> -                }
> -            }
> -        }
> -    }
> -}
> -
> -static void tlb_info_pae32(Monitor *mon, CPUArchState *env)
> -{
> -    unsigned int l1, l2, l3;
> -    uint64_t pdpe, pde, pte;
> -    uint64_t pdp_addr, pd_addr, pt_addr;
> +    /* Trim line to fit screen */
> +    g_string_truncate(buf, 79);

Do we need that?  It's a pretty arbitrary limit these days.

> -    pdp_addr = env->cr[3] & ~0x1f;
> -    for (l1 = 0; l1 < 4; l1++) {
> -        cpu_physical_memory_read(pdp_addr + l1 * 8, &pdpe, 8);
> -        pdpe = le64_to_cpu(pdpe);
> -        if (pdpe & PG_PRESENT_MASK) {
> -            pd_addr = pdpe & 0x3fffffffff000ULL;
> -            for (l2 = 0; l2 < 512; l2++) {
> -                cpu_physical_memory_read(pd_addr + l2 * 8, &pde, 8);
> -                pde = le64_to_cpu(pde);
> -                if (pde & PG_PRESENT_MASK) {
> -                    if (pde & PG_PSE_MASK) {
> -                        /* 2M pages with PAE, CR4.PSE is ignored */
> -                        print_pte(mon, env, (l1 << 30) + (l2 << 21), pde,
> -                                  ~((hwaddr)(1 << 20) - 1));
> -                    } else {
> -                        pt_addr = pde & 0x3fffffffff000ULL;
> -                        for (l3 = 0; l3 < 512; l3++) {
> -                            cpu_physical_memory_read(pt_addr + l3 * 8, &pte, 8);
> -                            pte = le64_to_cpu(pte);
> -                            if (pte & PG_PRESENT_MASK) {
> -                                print_pte(mon, env, (l1 << 30) + (l2 << 21)
> -                                          + (l3 << 12),
> -                                          pte & ~PG_PSE_MASK,
> -                                          ~(hwaddr)0xfff);
> -                            }
> -                        }
> -                    }
> -                }
> -            }
> -        }
> -    }
> +    g_string_append_printf(out_buf, "%s\n", buf->str);
>  }
>  
> -#ifdef TARGET_X86_64
> -static void tlb_info_la48(Monitor *mon, CPUArchState *env,
> -        uint64_t l0, uint64_t pml4_addr)
> +static
> +int mem_print_tlb(CPUState *cs, void *data, DecodedPTE *pte, int height,
> +                  int offset, int mmu_idx, const PageTableLayout *layout)
>  {
> -    uint64_t l1, l2, l3, l4;
> -    uint64_t pml4e, pdpe, pde, pte;
> -    uint64_t pdp_addr, pd_addr, pt_addr;
> -
> -    for (l1 = 0; l1 < 512; l1++) {
> -        cpu_physical_memory_read(pml4_addr + l1 * 8, &pml4e, 8);
> -        pml4e = le64_to_cpu(pml4e);
> -        if (!(pml4e & PG_PRESENT_MASK)) {
> -            continue;
> -        }
> -
> -        pdp_addr = pml4e & 0x3fffffffff000ULL;
> -        for (l2 = 0; l2 < 512; l2++) {
> -            cpu_physical_memory_read(pdp_addr + l2 * 8, &pdpe, 8);
> -            pdpe = le64_to_cpu(pdpe);
> -            if (!(pdpe & PG_PRESENT_MASK)) {
> -                continue;
> -            }
> +    struct mem_print_state *state = (struct mem_print_state *) data;
> +    CPUClass *cc = CPU_GET_CLASS(cs);
>  
> -            if (pdpe & PG_PSE_MASK) {
> -                /* 1G pages, CR4.PSE is ignored */
> -                print_pte(mon, env, (l0 << 48) + (l1 << 39) + (l2 << 30),
> -                        pdpe, 0x3ffffc0000000ULL);
> -                continue;
> -            }
> -
> -            pd_addr = pdpe & 0x3fffffffff000ULL;
> -            for (l3 = 0; l3 < 512; l3++) {
> -                cpu_physical_memory_read(pd_addr + l3 * 8, &pde, 8);
> -                pde = le64_to_cpu(pde);
> -                if (!(pde & PG_PRESENT_MASK)) {
> -                    continue;
> -                }
> +    cc->sysemu_ops->mon_print_pte(cs, state->buf, pte->bits_translated,
> +                                  pte->child, pte->prot, mmu_idx);
>  
> -                if (pde & PG_PSE_MASK) {
> -                    /* 2M pages, CR4.PSE is ignored */
> -                    print_pte(mon, env, (l0 << 48) + (l1 << 39) + (l2 << 30) +
> -                            (l3 << 21), pde, 0x3ffffffe00000ULL);
> -                    continue;
> -                }
> -
> -                pt_addr = pde & 0x3fffffffff000ULL;
> -                for (l4 = 0; l4 < 512; l4++) {
> -                    cpu_physical_memory_read(pt_addr
> -                            + l4 * 8,
> -                            &pte, 8);
> -                    pte = le64_to_cpu(pte);
> -                    if (pte & PG_PRESENT_MASK) {
> -                        print_pte(mon, env, (l0 << 48) + (l1 << 39) +
> -                                (l2 << 30) + (l3 << 21) + (l4 << 12),
> -                                pte & ~PG_PSE_MASK, 0x3fffffffff000ULL);
> -                    }
> -                }
> -            }
> -        }
> -    }
> +    return 0;
>  }
>  
> -static void tlb_info_la57(Monitor *mon, CPUArchState *env)
> +static
> +void helper_hmp_info_tlb(CPUState *cs, Monitor *mon, int mmu_idx)
>  {
> -    uint64_t l0;
> -    uint64_t pml5e;
> -    uint64_t pml5_addr;
> +    struct mem_print_state state;
> +    g_autoptr(GString) buf = g_string_new("");
> +    CPUClass *cc = CPU_GET_CLASS(cs);
>  
> -    pml5_addr = env->cr[3] & 0x3fffffffff000ULL;
> -    for (l0 = 0; l0 < 512; l0++) {
> -        cpu_physical_memory_read(pml5_addr + l0 * 8, &pml5e, 8);
> -        pml5e = le64_to_cpu(pml5e);
> -        if (pml5e & PG_PRESENT_MASK) {
> -            tlb_info_la48(mon, env, l0, pml5e & 0x3fffffffff000ULL);
> -        }
> +    if (!cc->sysemu_ops->mon_init_page_table_iterator(cs, buf, mmu_idx,
> +                                                      &state)) {
> +        monitor_printf(mon, "Unable to initialize page table iterator\n");
> +        return;
>      }
> +
> +    /**
> +     * 'info tlb' visits only leaf PTEs marked present.
> +     * It does not check other protection bits.

(What happens if the guest is using huge pages inside the guest?)

> +     */
> +    for_each_pte(cs, &mem_print_tlb, &state, false, false, false,  mmu_idx);
> +
> +    monitor_printf(mon, "%s", buf->str);
>  }
> -#endif /* TARGET_X86_64 */
>  
>  void hmp_info_tlb(Monitor *mon, const QDict *qdict)
>  {
> -    CPUArchState *env;
> +    CPUState *cs = mon_get_cpu(mon);
> +    bool nested;
>  
> -    env = mon_get_cpu_env(mon);
> -    if (!env) {
> -        monitor_printf(mon, "No CPU available\n");
> +    if (!cs) {
> +        monitor_printf(mon, "Unable to get CPUState.  Internal error\n");

I wouldn't bother saying ' Internal error'.

>          return;
>      }
>  
> -    if (!(env->cr[0] & CR0_PG_MASK)) {
> +    if (!cpu_paging_enabled(cs, 0)) {
>          monitor_printf(mon, "PG disabled\n");
>          return;
>      }
> -    if (env->cr[4] & CR4_PAE_MASK) {
> -#ifdef TARGET_X86_64
> -        if (env->hflags & HF_LMA_MASK) {
> -            if (env->cr[4] & CR4_LA57_MASK) {
> -                tlb_info_la57(mon, env);
> -            } else {
> -                tlb_info_la48(mon, env, 0, env->cr[3] & 0x3fffffffff000ULL);
> -            }
> -        } else
> -#endif
> -        {
> -            tlb_info_pae32(mon, env);
> -        }
> -    } else {
> -        tlb_info_32(mon, env);
> +
> +    CPUClass *cc = CPU_GET_CLASS(cs);
> +
> +    if (!cc->sysemu_ops->mon_print_pte
> +        || !cc->sysemu_ops->mon_init_page_table_iterator) {
> +        monitor_printf(mon, "Info tlb unsupported on this ISA\n");
> +        return;
> +    }
> +
> +    nested = cpu_paging_enabled(cs, 1);
> +
> +    if (nested) {
> +        monitor_printf(mon,
> +                       "Info guest TLB (guest virtual to guest physical):\n");
> +    }
> +
> +    helper_hmp_info_tlb(cs, mon, 0);
> +
> +    if (nested) {
> +        monitor_printf(mon,
> +                       "Info host TLB, (guest physical to host physical):\n");
> +
> +        helper_hmp_info_tlb(cs, mon, 1);
> +
>      }
>  }
>  
> -- 
> 2.34.1
> 
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/