[PATCH v1 5/8]: PVH smp changes

[PATCH v1 5/8]: PVH smp changes

[Mukesh Rathor]

---
 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 f58dca7..e1e8582 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->gdt_frames[0] = (unsigned long)gdt;
+		ctxt->gdt_ents = (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->gdt_frames[0] = gdt_mfn;
-	ctxt->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->gdt_frames[0] = gdt_mfn;
+		ctxt->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

Re: [PATCH v1 5/8]: PVH smp changes

[Stefano Stabellini]

On Fri, 21 Sep 2012, Mukesh Rathor wrote:
> ---
>  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 f58dca7..e1e8582 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);
> +	}

it is worth adding a comment saying that PVH doesn't need this even if
the pagetable are writable in that case