linux-user: Speed up guest space initialization on 32-bit ARM target

[Qemu-devel] [PATCH 02/10] linux-user: Rename validate_guest_space => init_guest_commpage

Posted by Luke Shumaker 7 years, 10 months ago

From: Luke Shumaker <lukeshu@parabola.nu>

init_guest_commpage is a much more honest description of what the function
does.  validate_guest_space not only suggests that the function has no
side-effects, but also introduces confusion as to why it is only needed on
32-bit ARM targets.

Signed-off-by: Luke Shumaker <lukeshu@parabola.nu>
---
 linux-user/elfload.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index cac991159c..453394239c 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -362,8 +362,8 @@ enum {
  * The guest code may leave a page mapped and populate it if the
  * address is suitable.
  */
-static int validate_guest_space(unsigned long guest_base,
-                                unsigned long guest_size)
+static int init_guest_commpage(unsigned long guest_base,
+                               unsigned long guest_size)
 {
     unsigned long real_start, test_page_addr;
 
@@ -1836,7 +1836,7 @@ unsigned long init_guest_space(unsigned long host_start,
      * address.  */
     if (host_start && !host_size) {
 #if defined(TARGET_ARM) && !defined(TARGET_AARCH64)
-        if (validate_guest_space(host_start, host_size) == 1) {
+        if (init_guest_commpage(host_start, host_size) != 1) {
             return (unsigned long)-1;
         }
 #endif
@@ -1881,8 +1881,8 @@ unsigned long init_guest_space(unsigned long host_start,
         if (!host_start || real_start == current_start) {
 #if defined(TARGET_ARM) && !defined(TARGET_AARCH64)
             /* On 32-bit ARM, we need to also be able to map the commpage.  */
-            int valid = validate_guest_space(real_start - guest_start,
-                                             real_size);
+            int valid = init_guest_commpage(real_start - guest_start,
+                                            real_size);
             if (valid == 1) {
                 break;
             } else if (valid == -1) {
-- 
2.15.1

Re: [Qemu-devel] [PATCH 02/10] linux-user: Rename validate_guest_space => init_guest_commpage

Posted by Peter Maydell 7 years, 7 months ago

On 28 December 2017 at 18:08, Luke Shumaker <lukeshu@lukeshu.com> wrote:
> From: Luke Shumaker <lukeshu@parabola.nu>
>
> init_guest_commpage is a much more honest description of what the function
> does.  validate_guest_space not only suggests that the function has no
> side-effects, but also introduces confusion as to why it is only needed on
> 32-bit ARM targets.
>
> Signed-off-by: Luke Shumaker <lukeshu@parabola.nu>
> ---
>  linux-user/elfload.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index cac991159c..453394239c 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -362,8 +362,8 @@ enum {
>   * The guest code may leave a page mapped and populate it if the
>   * address is suitable.
>   */
> -static int validate_guest_space(unsigned long guest_base,
> -                                unsigned long guest_size)
> +static int init_guest_commpage(unsigned long guest_base,
> +                               unsigned long guest_size)
>  {
>      unsigned long real_start, test_page_addr;
>
> @@ -1836,7 +1836,7 @@ unsigned long init_guest_space(unsigned long host_start,
>       * address.  */
>      if (host_start && !host_size) {
>  #if defined(TARGET_ARM) && !defined(TARGET_AARCH64)
> -        if (validate_guest_space(host_start, host_size) == 1) {
> +        if (init_guest_commpage(host_start, host_size) != 1) {

this is the bit that includes the '==' to '!=' change that should
be in patch 1.

Otherwise

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM

Re: [Qemu-devel] [PATCH 02/10] linux-user: Rename validate_guest_space => init_guest_commpage

Posted by Laurent Vivier 7 years, 7 months ago

Le 28/12/2017 à 19:08, Luke Shumaker a écrit :
> From: Luke Shumaker <lukeshu@parabola.nu>
> 
> init_guest_commpage is a much more honest description of what the function
> does.  validate_guest_space not only suggests that the function has no
> side-effects, but also introduces confusion as to why it is only needed on
> 32-bit ARM targets.
> 
> Signed-off-by: Luke Shumaker <lukeshu@parabola.nu>
> ---
>  linux-user/elfload.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 

Applied to my 'linux-user-for-2.12' branch.

Thanks,
Laurent