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Date: Mon, 22 Oct 2012 11:40:49 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
"mukesh.rathor@...cle.com" <mukesh.rathor@...cle.com>,
Ian Campbell <Ian.Campbell@...rix.com>
Subject: Re: [PATCH 2/6] xen/pvh: Extend vcpu_guest_context, p2m, event, and
xenbus to support PVH.
On Mon, Oct 22, 2012 at 02:44:40PM +0100, Stefano Stabellini wrote:
> On Sat, 20 Oct 2012, Konrad Rzeszutek Wilk wrote:
> > From: Mukesh Rathor <mukesh.rathor@...cle.com>
> >
> > make gdt_frames[]/gdt_ents into a union with {gdtaddr, gdtsz}, as PVH
> > only needs to send down gdtaddr and gdtsz.
> >
> > For interrupts, PVH uses native_irq_ops.
> > vcpu hotplug is currently not available for PVH.
> >
> > For events we follow what PVHVM does - to use callback vector.
> > Lastly, also use HVM path to setup XenBus.
> >
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> > ---
> > arch/x86/include/asm/xen/interface.h | 11 +++++-
> > arch/x86/xen/irq.c | 5 ++-
> > arch/x86/xen/p2m.c | 2 +-
> > arch/x86/xen/smp.c | 75 ++++++++++++++++++++++------------
> > drivers/xen/cpu_hotplug.c | 4 +-
> > drivers/xen/events.c | 9 ++++-
> > drivers/xen/xenbus/xenbus_client.c | 3 +-
> > 7 files changed, 77 insertions(+), 32 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/xen/interface.h b/arch/x86/include/asm/xen/interface.h
> > index 6d2f75a..4c08f23 100644
> > --- a/arch/x86/include/asm/xen/interface.h
> > +++ b/arch/x86/include/asm/xen/interface.h
> > @@ -144,7 +144,16 @@ struct vcpu_guest_context {
> > struct cpu_user_regs user_regs; /* User-level CPU registers */
> > struct trap_info trap_ctxt[256]; /* Virtual IDT */
> > unsigned long ldt_base, ldt_ents; /* LDT (linear address, # ents) */
> > - unsigned long gdt_frames[16], gdt_ents; /* GDT (machine frames, # ents) */
> > + union {
> > + struct {
> > + /* PV: GDT (machine frames, # ents).*/
> > + unsigned long gdt_frames[16], gdt_ents;
> > + } pv;
> > + struct {
> > + /* PVH: GDTR addr and size */
> > + unsigned long gdtaddr, gdtsz;
> > + } pvh;
> > + } u;
> > unsigned long kernel_ss, kernel_sp; /* Virtual TSS (only SS1/SP1) */
> > /* NB. User pagetable on x86/64 is placed in ctrlreg[1]. */
> > unsigned long ctrlreg[8]; /* CR0-CR7 (control registers) */
> > diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
> > index 01a4dc0..fcbe56a 100644
> > --- a/arch/x86/xen/irq.c
> > +++ b/arch/x86/xen/irq.c
> > @@ -5,6 +5,7 @@
> > #include <xen/interface/xen.h>
> > #include <xen/interface/sched.h>
> > #include <xen/interface/vcpu.h>
> > +#include <xen/features.h>
> > #include <xen/events.h>
> >
> > #include <asm/xen/hypercall.h>
> > @@ -129,6 +130,8 @@ static const struct pv_irq_ops xen_irq_ops __initconst = {
> >
> > void __init xen_init_irq_ops(void)
> > {
> > - pv_irq_ops = xen_irq_ops;
> > + /* For PVH we use default pv_irq_ops settings */
> > + if (!xen_feature(XENFEAT_hvm_callback_vector))
> > + pv_irq_ops = xen_irq_ops;
> > x86_init.irqs.intr_init = xen_init_IRQ;
> > }
> > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> > index 95fb2aa..ea553c8 100644
> > --- a/arch/x86/xen/p2m.c
> > +++ b/arch/x86/xen/p2m.c
> > @@ -798,7 +798,7 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> > {
> > unsigned topidx, mididx, idx;
> >
> > - if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
> > + if (xen_feature(XENFEAT_auto_translated_physmap)) {
> > BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
> > return true;
> > }
> > diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> > index 353c50f..df400349 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 */
>
> I am not sure what this comment means, considering that in another
> comment below you say that we don't support 32bit PVH kernels.
Hm, even the V1 had this. I think he meant something else.
>
>
> > + 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.pvh.gdtaddr = (unsigned long)gdt;
> > + ctxt->u.pvh.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->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->u.pv.gdt_frames[0] = gdt_mfn;
> > + ctxt->u.pv.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));
>
> The tradional path looks the same as before, however it is hard to tell
> whether the PVH path is correct without the Xen side. For example, what
> is gdtsz?
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