diff mbox series

[1/6] x86/boot: Check for E820_RAM earlier when searching the E820

Message ID 20200106155423.9508-2-andrew.cooper3@citrix.com (mailing list archive)
State Superseded
Headers show
Series x86/boot: Remove mappings at 0 | expand

Commit Message

Andrew Cooper Jan. 6, 2020, 3:54 p.m. UTC 
There is no point performing the masking calculations if we are going to
throw the result away.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wl@xen.org>
CC: Roger Pau Monné <roger.pau@citrix.com>
---
 xen/arch/x86/setup.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Comments

Jan Beulich Jan. 7, 2020, 3:12 p.m. UTC | #1 
On 06.01.2020 16:54, Andrew Cooper wrote:
> There is no point performing the masking calculations if we are going to
> throw the result away.

A reasonably optimizing compiler ought to do so. It's slightly less
source code the original way. Nevertheless I don't really mind the
change, so ...

> No functional change.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>
diff mbox series

Patch

diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 501f3f5e4b..ed54f79fea 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1033,11 +1033,14 @@  void __init noreturn __start_xen(unsigned long mbi_p)
         uint64_t s, e, mask = (1UL << L2_PAGETABLE_SHIFT) - 1;
         uint64_t end, limit = ARRAY_SIZE(l2_identmap) << L2_PAGETABLE_SHIFT;
 
+        if ( boot_e820.map[i].type != E820_RAM )
+            continue;
+
         /* Superpage-aligned chunks from BOOTSTRAP_MAP_BASE. */
         s = (boot_e820.map[i].addr + mask) & ~mask;
         e = (boot_e820.map[i].addr + boot_e820.map[i].size) & ~mask;
         s = max_t(uint64_t, s, BOOTSTRAP_MAP_BASE);
-        if ( (boot_e820.map[i].type != E820_RAM) || (s >= e) )
+        if ( s >= e )
             continue;
 
         if ( s < limit )
@@ -1286,11 +1289,14 @@  void __init noreturn __start_xen(unsigned long mbi_p)
         uint64_t s, e, mask = PAGE_SIZE - 1;
         uint64_t map_s, map_e;
 
+        if ( boot_e820.map[i].type != E820_RAM )
+            continue;
+
         /* Only page alignment required now. */
         s = (boot_e820.map[i].addr + mask) & ~mask;
         e = (boot_e820.map[i].addr + boot_e820.map[i].size) & ~mask;
         s = max_t(uint64_t, s, 1<<20);
-        if ( (boot_e820.map[i].type != E820_RAM) || (s >= e) )
+        if ( s >= e )
             continue;
 
         if ( !acpi_boot_table_init_done &&