[PATCH] x86: GDT alignment fix

Make GDT page aligned and page padded to support running inside of a
hypervisor.  This prevents false sharing of the GDT page with other hot
data, which is not allowed in Xen, and causes performance problems in
VMware.

Rather than go back to the old method of statically allocating the GDT
(which wastes unneded space for non-present CPUs), the GDT for APs is
allocated dynamically.

Signed-off-by: Zachary Amsden <zach@vmware.com>
Cc: "Seth, Rohit" <rohit.seth@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 9 deletions

diff --git a/drivers/pnp/pnpbios/bioscalls.c b/drivers/pnp/pnpbios/bioscalls.c
index 6b7583f497d0..7cb476ed7f91 100644
--- a/drivers/pnp/pnpbios/bioscalls.c
+++ b/drivers/pnp/pnpbios/bioscalls.c
@@ -69,14 +69,16 @@ __asm__(
 
 #define Q_SET_SEL(cpu, selname, address, size) \
 do { \
-set_base(per_cpu(cpu_gdt_table,cpu)[(selname) >> 3], __va((u32)(address))); \
-set_limit(per_cpu(cpu_gdt_table,cpu)[(selname) >> 3], size); \
+struct desc_struct *gdt = get_cpu_gdt_table((cpu)); \
+set_base(gdt[(selname) >> 3], __va((u32)(address))); \
+set_limit(gdt[(selname) >> 3], size); \
 } while(0)
 
 #define Q2_SET_SEL(cpu, selname, address, size) \
 do { \
-set_base(per_cpu(cpu_gdt_table,cpu)[(selname) >> 3], (u32)(address)); \
-set_limit(per_cpu(cpu_gdt_table,cpu)[(selname) >> 3], size); \
+struct desc_struct *gdt = get_cpu_gdt_table((cpu)); \
+set_base(gdt[(selname) >> 3], (u32)(address)); \
+set_limit(gdt[(selname) >> 3], size); \
 } while(0)
 
 static struct desc_struct bad_bios_desc = { 0, 0x00409200 };
@@ -115,8 +117,8 @@ static inline u16 call_pnp_bios(u16 func, u16 arg1, u16 arg2, u16 arg3,
                 return PNP_FUNCTION_NOT_SUPPORTED;
 
         cpu = get_cpu();
-        save_desc_40 = per_cpu(cpu_gdt_table,cpu)[0x40 / 8];
-        per_cpu(cpu_gdt_table,cpu)[0x40 / 8] = bad_bios_desc;
+        save_desc_40 = get_cpu_gdt_table(cpu)[0x40 / 8];
+        get_cpu_gdt_table(cpu)[0x40 / 8] = bad_bios_desc;
 
         /* On some boxes IRQ's during PnP BIOS calls are deadly.  */
         spin_lock_irqsave(&pnp_bios_lock, flags);
@@ -158,7 +160,7 @@ static inline u16 call_pnp_bios(u16 func, u16 arg1, u16 arg2, u16 arg3,
         );
         spin_unlock_irqrestore(&pnp_bios_lock, flags);
 
-        per_cpu(cpu_gdt_table,cpu)[0x40 / 8] = save_desc_40;
+        get_cpu_gdt_table(cpu)[0x40 / 8] = save_desc_40;
         put_cpu();
 
         /* If we get here and this is set then the PnP BIOS faulted on us. */
@@ -535,8 +537,10 @@ void pnpbios_calls_init(union pnp_bios_install_struct *header)
 
         set_base(bad_bios_desc, __va((unsigned long)0x40 << 4));
         _set_limit((char *)&bad_bios_desc, 4095 - (0x40 << 4));
-        for(i=0; i < NR_CPUS; i++)
-        {
+        for (i = 0; i < NR_CPUS; i++) {
+                struct desc_struct *gdt = get_cpu_gdt_table(i);
+                if (!gdt)
+                        continue;
                 Q2_SET_SEL(i, PNP_CS32, &pnp_bios_callfunc, 64 * 1024);
                 Q_SET_SEL(i, PNP_CS16, header->fields.pm16cseg, 64 * 1024);
                 Q_SET_SEL(i, PNP_DS, header->fields.pm16dseg, 64 * 1024);