[PATCH v2 0/2] Minor improvement to early boot code

[PATCH v2 0/2] Minor improvement to early boot code

[Wei Liu]

Wei Liu (2):
  x86: make sure module array is large enough in pvh-boot.c
  xen: initialise opt_xen_console early in PVH boot path

 xen/arch/x86/guest/pvh-boot.c | 12 +++++++++++-
 xen/arch/x86/setup.c          |  5 +++++
 xen/drivers/char/console.c    | 10 ++++++++--
 xen/include/xen/console.h     |  2 ++
 4 files changed, 26 insertions(+), 3 deletions(-)

-- 
2.11.0


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[PATCH v2 1/2] x86: make sure module array is large enough in pvh-boot.c

[Wei Liu]

The relocation code in __start_xen requires one extra element in the
module array. By the looks of it the temporary array is already large
enough. Panic if that's not the case.

While at it, turn an ASSERT to panic() as well.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 xen/arch/x86/guest/pvh-boot.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/guest/pvh-boot.c b/xen/arch/x86/guest/pvh-boot.c
index 0e9e5bfdf6..3b44aee90a 100644
--- a/xen/arch/x86/guest/pvh-boot.c
+++ b/xen/arch/x86/guest/pvh-boot.c
@@ -42,7 +42,17 @@ static void __init convert_pvh_info(void)
     module_t *mod;
     unsigned int i;
 
-    ASSERT(pvh_info->magic == XEN_HVM_START_MAGIC_VALUE);
+    if ( pvh_info->magic != XEN_HVM_START_MAGIC_VALUE )
+        panic("Magic value is wrong: %X\n", pvh_info->magic);
+
+    /*
+     * Temporary module array needs to be at least one element bigger than
+     * required. The extra element is used to aid relocation. See
+     * arch/x86/setup.c:__start_xen().
+     */
+    if ( ARRAY_SIZE(pvh_mbi_mods) <= pvh_info->nr_modules )
+        panic("The module array is too small, size %lu, requested %u.\n",
+              ARRAY_SIZE(pvh_mbi_mods), pvh_info->nr_modules);
 
     /*
      * Turn hvm_start_info into mbi. Luckily all modules are placed under 4GB
-- 
2.11.0


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[PATCH v2 2/2] xen: initialise opt_xen_console early in PVH boot path

[Wei Liu]

This helps capture issues before console is initialised.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 xen/arch/x86/setup.c       |  5 +++++
 xen/drivers/char/console.c | 10 ++++++++--
 xen/include/xen/console.h  |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 2fbf7d574c..20cb0acc3f 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -708,6 +708,11 @@ void __init noreturn __start_xen(unsigned long mbi_p)
 
     if ( pvh_boot )
     {
+        /*
+         * Force xen console to be enabled. We will reset it later in console
+         * initialisation code.
+         */
+        opt_console_xen = -1;
         ASSERT(mbi_p == 0);
         mbi = pvh_init();
     }
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index e48039dd82..3b75f7a472 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -91,7 +91,8 @@ static uint32_t conringc, conringp;
 static int __read_mostly sercon_handle = -1;
 
 #ifdef CONFIG_X86
-static bool __read_mostly opt_console_xen; /* console=xen */
+/* Tristate: 0 disabled, 1 user enabled, -1 default enabled */
+int8_t __read_mostly opt_console_xen; /* console=xen */
 #endif
 
 static DEFINE_SPINLOCK(console_lock);
@@ -832,7 +833,7 @@ void __init console_init_preirq(void)
             pv_console_init();
 #ifdef CONFIG_X86
         else if ( !strncmp(p, "xen", 3) )
-            opt_console_xen = true;
+            opt_console_xen = 1;
 #endif
         else if ( !strncmp(p, "none", 4) )
             continue;
@@ -852,6 +853,11 @@ void __init console_init_preirq(void)
         }
     }
 
+#ifdef CONFIG_X86
+    if ( opt_console_xen == -1 )
+        opt_console_xen = 0;
+#endif
+
     serial_set_rx_handler(sercon_handle, serial_rx);
     pv_console_set_rx_handler(serial_rx);
 
diff --git a/xen/include/xen/console.h b/xen/include/xen/console.h
index ea06fd8078..70c9911a49 100644
--- a/xen/include/xen/console.h
+++ b/xen/include/xen/console.h
@@ -43,4 +43,6 @@ void console_giveback(int id);
 int console_suspend(void);
 int console_resume(void);
 
+extern int8_t opt_console_xen;
+
 #endif /* __CONSOLE_H__ */
-- 
2.11.0


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Re: [PATCH v2 1/2] x86: make sure module array is large enough in pvh-boot.c

[Andrew Cooper]

On 28/09/18 18:06, Wei Liu wrote:
> diff --git a/xen/arch/x86/guest/pvh-boot.c b/xen/arch/x86/guest/pvh-boot.c
> index 0e9e5bfdf6..3b44aee90a 100644
> --- a/xen/arch/x86/guest/pvh-boot.c
> +++ b/xen/arch/x86/guest/pvh-boot.c
> @@ -42,7 +42,17 @@ static void __init convert_pvh_info(void)
>      module_t *mod;
>      unsigned int i;
>  
> -    ASSERT(pvh_info->magic == XEN_HVM_START_MAGIC_VALUE);
> +    if ( pvh_info->magic != XEN_HVM_START_MAGIC_VALUE )
> +        panic("Magic value is wrong: %X\n", pvh_info->magic);

%x ?

> +
> +    /*
> +     * Temporary module array needs to be at least one element bigger than
> +     * required. The extra element is used to aid relocation. See
> +     * arch/x86/setup.c:__start_xen().
> +     */
> +    if ( ARRAY_SIZE(pvh_mbi_mods) <= pvh_info->nr_modules )
> +        panic("The module array is too small, size %lu, requested %u.\n",

%zu for size_t, and please drop the unnecessary trailing .

Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

> +              ARRAY_SIZE(pvh_mbi_mods), pvh_info->nr_modules);
>  
>      /*
>       * Turn hvm_start_info into mbi. Luckily all modules are placed under 4GB


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Re: [PATCH v2 2/2] xen: initialise opt_xen_console early in PVH boot path

[Andrew Cooper]

On 28/09/18 18:06, Wei Liu wrote:
> This helps capture issues before console is initialised.
>
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>

Much nicer behaviour.

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

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