[PATCH V2 5/7]: PVH: smp changes.

[Mukesh Rathor <mukesh.rathor@oracle.com>]

PVH: smp changes. This pertains to bringing up smp vcpus. PVH runs in
ring 0, so syscalls are native. Also, the vcpu context is send down via
the hcall to be set in the vmcs. gdtaddr and gdtsz are unionionized as
PVH only needs to send these two to be set in the vmcs

Signed-off-by: Mukesh R <mukesh.rathor@oracle.com>
---
 arch/x86/xen/smp.c |   75 ++++++++++++++++++++++++++++++++++------------------
 1 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index bd92698..63a0bfb 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -68,9 +68,11 @@ static void __cpuinit cpu_bringup(void)
 	touch_softlockup_watchdog();
 	preempt_disable();
 
-	xen_enable_sysenter();
-	xen_enable_syscall();
-
+	/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
+	if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
+		xen_enable_sysenter();
+		xen_enable_syscall();
+	}
 	cpu = smp_processor_id();
 	smp_store_cpu_info(cpu);
 	cpu_data(cpu).x86_max_cores = 1;
@@ -230,10 +232,11 @@ static void __init xen_smp_prepare_boot_cpu(void)
 	BUG_ON(smp_processor_id() != 0);
 	native_smp_prepare_boot_cpu();
 
-	/* We've switched to the "real" per-cpu gdt, so make sure the
-	   old memory can be recycled */
-	make_lowmem_page_readwrite(xen_initial_gdt);
-
+	if (!xen_feature(XENFEAT_writable_page_tables)) {
+		/* We've switched to the "real" per-cpu gdt, so make sure the
+		 * old memory can be recycled */
+		make_lowmem_page_readwrite(xen_initial_gdt);
+	}
 	xen_filter_cpu_maps();
 	xen_setup_vcpu_info_placement();
 }
@@ -300,8 +303,6 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 	gdt = get_cpu_gdt_table(cpu);
 
 	ctxt->flags = VGCF_IN_KERNEL;
-	ctxt->user_regs.ds = __USER_DS;
-	ctxt->user_regs.es = __USER_DS;
 	ctxt->user_regs.ss = __KERNEL_DS;
 #ifdef CONFIG_X86_32
 	ctxt->user_regs.fs = __KERNEL_PERCPU;
@@ -310,35 +311,57 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
 	ctxt->gs_base_kernel = per_cpu_offset(cpu);
 #endif
 	ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
-	ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
 
 	memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
 
-	xen_copy_trap_info(ctxt->trap_ctxt);
+	/* check for autoxlated to get it right for 32bit kernel */
+	if (xen_feature(XENFEAT_auto_translated_physmap) &&
+	    xen_feature(XENFEAT_supervisor_mode_kernel)) {
 
-	ctxt->ldt_ents = 0;
+		ctxt->user_regs.ds = __KERNEL_DS;
+		ctxt->user_regs.es = 0;
+		ctxt->user_regs.gs = 0;
 
-	BUG_ON((unsigned long)gdt & ~PAGE_MASK);
+		ctxt->u.gdtaddr = (unsigned long)gdt;
+		ctxt->u.gdtsz = (unsigned long)(GDT_SIZE - 1);
 
-	gdt_mfn = arbitrary_virt_to_mfn(gdt);
-	make_lowmem_page_readonly(gdt);
-	make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
+#ifdef CONFIG_X86_64
+		/* Note: PVH is not supported on x86_32. */
+		ctxt->gs_base_user = (unsigned long)
+					per_cpu(irq_stack_union.gs_base, cpu);
+#endif
+	} else {
+		ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
+		ctxt->user_regs.ds = __USER_DS;
+		ctxt->user_regs.es = __USER_DS;
 
-	ctxt->u.s.gdt_frames[0] = gdt_mfn;
-	ctxt->u.s.gdt_ents      = GDT_ENTRIES;
+		xen_copy_trap_info(ctxt->trap_ctxt);
 
-	ctxt->user_regs.cs = __KERNEL_CS;
-	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
+		ctxt->ldt_ents = 0;
 
-	ctxt->kernel_ss = __KERNEL_DS;
-	ctxt->kernel_sp = idle->thread.sp0;
+		BUG_ON((unsigned long)gdt & ~PAGE_MASK);
+
+		gdt_mfn = arbitrary_virt_to_mfn(gdt);
+		make_lowmem_page_readonly(gdt);
+		make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
+
+		ctxt->u.s.gdt_frames[0] = gdt_mfn;
+		ctxt->u.s.gdt_ents      = GDT_ENTRIES;
+
+		ctxt->kernel_ss = __KERNEL_DS;
+		ctxt->kernel_sp = idle->thread.sp0;
 
 #ifdef CONFIG_X86_32
-	ctxt->event_callback_cs     = __KERNEL_CS;
-	ctxt->failsafe_callback_cs  = __KERNEL_CS;
+		ctxt->event_callback_cs     = __KERNEL_CS;
+		ctxt->failsafe_callback_cs  = __KERNEL_CS;
 #endif
-	ctxt->event_callback_eip    = (unsigned long)xen_hypervisor_callback;
-	ctxt->failsafe_callback_eip = (unsigned long)xen_failsafe_callback;
+		ctxt->event_callback_eip    =
+					(unsigned long)xen_hypervisor_callback;
+		ctxt->failsafe_callback_eip =
+					(unsigned long)xen_failsafe_callback;
+	}
+	ctxt->user_regs.cs = __KERNEL_CS;
+	ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
 
 	per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
 	ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
-- 
1.7.2.3