[v3] linux-user: Improve host and guest page size handling

[PATCH v3 01/33] accel/tcg: Remove qemu_host_page_size from page_protect/page_unprotect

Posted by Richard Henderson 10 months, 4 weeks ago

Use qemu_real_host_page_size instead.  Except for the final mprotect
within page_protect, we already handled host < target page size.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/user-exec.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 68b252cb8e..69b7429e31 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -651,16 +651,17 @@ void page_protect(tb_page_addr_t address)
 {
     PageFlagsNode *p;
     target_ulong start, last;
+    int host_page_size = qemu_real_host_page_size();
     int prot;
 
     assert_memory_lock();
 
-    if (qemu_host_page_size <= TARGET_PAGE_SIZE) {
+    if (host_page_size <= TARGET_PAGE_SIZE) {
         start = address & TARGET_PAGE_MASK;
         last = start + TARGET_PAGE_SIZE - 1;
     } else {
-        start = address & qemu_host_page_mask;
-        last = start + qemu_host_page_size - 1;
+        start = address & -host_page_size;
+        last = start + host_page_size - 1;
     }
 
     p = pageflags_find(start, last);
@@ -671,7 +672,7 @@ void page_protect(tb_page_addr_t address)
 
     if (unlikely(p->itree.last < last)) {
         /* More than one protection region covers the one host page. */
-        assert(TARGET_PAGE_SIZE < qemu_host_page_size);
+        assert(TARGET_PAGE_SIZE < host_page_size);
         while ((p = pageflags_next(p, start, last)) != NULL) {
             prot |= p->flags;
         }
@@ -679,7 +680,7 @@ void page_protect(tb_page_addr_t address)
 
     if (prot & PAGE_WRITE) {
         pageflags_set_clear(start, last, 0, PAGE_WRITE);
-        mprotect(g2h_untagged(start), qemu_host_page_size,
+        mprotect(g2h_untagged(start), last - start + 1,
                  prot & (PAGE_READ | PAGE_EXEC) ? PROT_READ : PROT_NONE);
     }
 }
@@ -725,18 +726,19 @@ int page_unprotect(target_ulong address, uintptr_t pc)
         }
 #endif
     } else {
+        int host_page_size = qemu_real_host_page_size();
         target_ulong start, len, i;
         int prot;
 
-        if (qemu_host_page_size <= TARGET_PAGE_SIZE) {
+        if (host_page_size <= TARGET_PAGE_SIZE) {
             start = address & TARGET_PAGE_MASK;
             len = TARGET_PAGE_SIZE;
             prot = p->flags | PAGE_WRITE;
             pageflags_set_clear(start, start + len - 1, PAGE_WRITE, 0);
             current_tb_invalidated = tb_invalidate_phys_page_unwind(start, pc);
         } else {
-            start = address & qemu_host_page_mask;
-            len = qemu_host_page_size;
+            start = address & -host_page_size;
+            len = host_page_size;
             prot = 0;
 
             for (i = 0; i < len; i += TARGET_PAGE_SIZE) {
-- 
2.34.1

Re: [PATCH v3 01/33] accel/tcg: Remove qemu_host_page_size from page_protect/page_unprotect

Posted by Ilya Leoshkevich 10 months ago

On Tue, Jan 02, 2024 at 12:57:36PM +1100, Richard Henderson wrote:
> Use qemu_real_host_page_size instead.  Except for the final mprotect
> within page_protect, we already handled host < target page size.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  accel/tcg/user-exec.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)

Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>

Re: [PATCH v3 01/33] accel/tcg: Remove qemu_host_page_size from page_protect/page_unprotect

Posted by Philippe Mathieu-Daudé 10 months, 4 weeks ago

On 2/1/24 02:57, Richard Henderson wrote:
> Use qemu_real_host_page_size instead.  Except for the final mprotect
> within page_protect, we already handled host < target page size.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   accel/tcg/user-exec.c | 18 ++++++++++--------
>   1 file changed, 10 insertions(+), 8 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>