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Message-Id: <1388777916-1328-12-git-send-email-konrad.wilk@oracle.com>
Date: Fri, 3 Jan 2014 14:38:28 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
boris.ostrovsky@...cle.com, stefano.stabellini@...citrix.com,
david.vrabel@...rix.com
Cc: hpa@...or.com, Mukesh Rathor <mukesh.rathor@...cle.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: [PATCH v13 11/19] xen/pvh: Secondary VCPU bringup (non-bootup CPUs)
From: Mukesh Rathor <mukesh.rathor@...cle.com>
The VCPU bringup protocol follows the PV with certain twists.
>From xen/include/public/arch-x86/xen.h:
Also note that when calling DOMCTL_setvcpucontext and VCPU_initialise
for HVM and PVH guests, not all information in this structure is updated:
- For HVM guests, the structures read include: fpu_ctxt (if
VGCT_I387_VALID is set), flags, user_regs, debugreg[*]
- PVH guests are the same as HVM guests, but additionally use ctrlreg[3] to
set cr3. All other fields not used should be set to 0.
This is what we do. We piggyback on the 'xen_setup_gdt' - but modify
a bit - we need to call 'load_percpu_segment' so that 'switch_to_new_gdt'
can load per-cpu data-structures. It has no effect on the VCPU0.
We also piggyback on the %rdi register to pass in the CPU number - so
that when we bootup a new CPU, the cpu_bringup_and_idle will have
passed as the first parameter the CPU number (via %rdi for 64-bit).
Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
arch/x86/xen/enlighten.c | 11 ++++++++---
arch/x86/xen/smp.c | 49 ++++++++++++++++++++++++++++++++----------------
arch/x86/xen/xen-ops.h | 1 +
3 files changed, 42 insertions(+), 19 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 1170d00..fde62c4 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1409,14 +1409,19 @@ static void __init xen_boot_params_init_edd(void)
* Set up the GDT and segment registers for -fstack-protector. Until
* we do this, we have to be careful not to call any stack-protected
* function, which is most of the kernel.
+ *
+ * Note, that it is refok - because the only caller of this after init
+ * is PVH which is not going to use xen_load_gdt_boot or other
+ * __init functions.
*/
-static void __init xen_setup_gdt(void)
+void __ref xen_setup_gdt(int cpu)
{
if (xen_feature(XENFEAT_auto_translated_physmap)) {
#ifdef CONFIG_X86_64
unsigned long dummy;
- switch_to_new_gdt(0); /* GDT and GS set */
+ load_percpu_segment(cpu); /* We need to access per-cpu area */
+ switch_to_new_gdt(cpu); /* GDT and GS set */
/* We are switching of the Xen provided GDT to our HVM mode
* GDT. The new GDT has __KERNEL_CS with CS.L = 1
@@ -1529,7 +1534,7 @@ asmlinkage void __init xen_start_kernel(void)
* Set up kernel GDT and segment registers, mainly so that
* -fstack-protector code can be executed.
*/
- xen_setup_gdt();
+ xen_setup_gdt(0);
xen_init_irq_ops();
xen_init_cpuid_mask();
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index c36b325..5e46190 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -73,9 +73,11 @@ static void 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;
@@ -97,8 +99,14 @@ static void cpu_bringup(void)
wmb(); /* make sure everything is out */
}
-static void cpu_bringup_and_idle(void)
+/* Note: cpu parameter is only relevant for PVH */
+static void cpu_bringup_and_idle(int cpu)
{
+#ifdef CONFIG_X86_64
+ if (xen_feature(XENFEAT_auto_translated_physmap) &&
+ xen_feature(XENFEAT_supervisor_mode_kernel))
+ xen_setup_gdt(cpu);
+#endif
cpu_bringup();
cpu_startup_entry(CPUHP_ONLINE);
}
@@ -274,9 +282,10 @@ static void __init xen_smp_prepare_boot_cpu(void)
native_smp_prepare_boot_cpu();
if (xen_pv_domain()) {
- /* 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);
#ifdef CONFIG_X86_32
/*
@@ -360,22 +369,21 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
gdt = get_cpu_gdt_table(cpu);
- ctxt->flags = VGCF_IN_KERNEL;
- ctxt->user_regs.ss = __KERNEL_DS;
#ifdef CONFIG_X86_32
+ /* Note: PVH is not yet supported on x86_32. */
ctxt->user_regs.fs = __KERNEL_PERCPU;
ctxt->user_regs.gs = __KERNEL_STACK_CANARY;
-#else
- ctxt->gs_base_kernel = per_cpu_offset(cpu);
#endif
ctxt->user_regs.eip = (unsigned long)cpu_bringup_and_idle;
memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
- {
+ if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+ ctxt->flags = VGCF_IN_KERNEL;
ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
ctxt->user_regs.ds = __USER_DS;
ctxt->user_regs.es = __USER_DS;
+ ctxt->user_regs.ss = __KERNEL_DS;
xen_copy_trap_info(ctxt->trap_ctxt);
@@ -396,18 +404,27 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
#ifdef CONFIG_X86_32
ctxt->event_callback_cs = __KERNEL_CS;
ctxt->failsafe_callback_cs = __KERNEL_CS;
+#else
+ ctxt->gs_base_kernel = per_cpu_offset(cpu);
#endif
ctxt->event_callback_eip =
(unsigned long)xen_hypervisor_callback;
ctxt->failsafe_callback_eip =
(unsigned long)xen_failsafe_callback;
+ ctxt->user_regs.cs = __KERNEL_CS;
+ per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
+#ifdef CONFIG_X86_32
}
- ctxt->user_regs.cs = __KERNEL_CS;
+#else
+ } else
+ /* N.B. The user_regs.eip (cpu_bringup_and_idle) is called with
+ * %rdi having the cpu number - which means are passing in
+ * as the first parameter the cpu. Subtle!
+ */
+ ctxt->user_regs.rdi = cpu;
+#endif
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));
-
if (HYPERVISOR_vcpu_op(VCPUOP_initialise, cpu, ctxt))
BUG();
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 95f8c61..9059c24 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -123,4 +123,5 @@ __visible void xen_adjust_exception_frame(void);
extern int xen_panic_handler_init(void);
+void xen_setup_gdt(int cpu);
#endif /* XEN_OPS_H */
--
1.8.3.1
--
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