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Message-ID: <alpine.DEB.2.02.1210231325130.2689@kaball.uk.xensource.com>
Date: Tue, 23 Oct 2012 13:25:48 +0100
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC: Mukesh Rathor <mukesh.rathor@...cle.com>,
Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.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, 22 Oct 2012, Konrad Rzeszutek Wilk wrote:
> On Mon, Oct 22, 2012 at 11:31:54AM -0700, Mukesh Rathor wrote:
> > On Mon, 22 Oct 2012 14:44:40 +0100
> > Stefano Stabellini <stefano.stabellini@...citrix.com> 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>
> > > > ---
> > > > return true;
> > > > }
> > > > - 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.
> >
> > Function is common to both 32bit and 64bit kernels. We need to check
> > for auto xlated also in the if statement in addition to supervisor
> > mode kernel, so 32 bit doesn't go down the wrong path.
>
> Can one just make it #ifdef CONFIG_X86_64 for the whole thing?
> You are either way during bootup doing a 'BUG' when booting as 32-bit?
>
>
> >
> > PVH is not supported for 32bit kernels, and gs_base_user doesn't exist
> > in the structure for 32bit so it needs to be if'def'd 64bit which is
> > ok because PVH is not supprted on 32bit kernel.
> >
> > > > + (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?
> >
> > gdtsz is GUEST_GDTR_LIMIT and gdtaddr is GUEST_GDTR_BASE in the vmcs.
>
> looking at this I figured it could be a bit neater. So I split it in
> two patches which should make it easier to read the PVH one.
It is much more readable now, thanks!
You can have my ack on both of them.
> >From f9455e293169d73e5698df62801bcd5fd64a5259 Mon Sep 17 00:00:00 2001
> From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Date: Mon, 22 Oct 2012 11:35:16 -0400
> Subject: [PATCH 1/2] xen/smp: Move the common CPU init code a bit to prep for
> PVH patch.
>
> The PV and PVH code CPU init code share some functionality. The
> PVH code ("xen/pvh: Extend vcpu_guest_context, p2m, event, and XenBus")
> sets some of these up, but not all. To make it easier to read, this
> patch removes the PV specific out of the generic way.
>
> No functional change, just code move.
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> ---
> arch/x86/xen/smp.c | 42 +++++++++++++++++++++++-------------------
> 1 files changed, 23 insertions(+), 19 deletions(-)
>
> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
> index 353c50f..ba49a3a 100644
> --- a/arch/x86/xen/smp.c
> +++ b/arch/x86/xen/smp.c
> @@ -300,8 +300,6 @@ 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 +308,41 @@ 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);
> + {
> + ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
> + ctxt->user_regs.ds = __USER_DS;
> + ctxt->user_regs.es = __USER_DS;
>
> - ctxt->ldt_ents = 0;
> + xen_copy_trap_info(ctxt->trap_ctxt);
>
> - BUG_ON((unsigned long)gdt & ~PAGE_MASK);
> + ctxt->ldt_ents = 0;
>
> - gdt_mfn = arbitrary_virt_to_mfn(gdt);
> - make_lowmem_page_readonly(gdt);
> - make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
> + BUG_ON((unsigned long)gdt & ~PAGE_MASK);
>
> - ctxt->gdt_frames[0] = gdt_mfn;
> - ctxt->gdt_ents = GDT_ENTRIES;
> + gdt_mfn = arbitrary_virt_to_mfn(gdt);
> + make_lowmem_page_readonly(gdt);
> + make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
>
> - ctxt->user_regs.cs = __KERNEL_CS;
> - ctxt->user_regs.esp = idle->thread.sp0 - sizeof(struct pt_regs);
> + 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;
> + 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));
> --
> 1.7.7.6
>
>
>
>
> >From 2c4dd7f567b229451f3dc1ae00d784da8b4a5072 Mon Sep 17 00:00:00 2001
> From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Date: Mon, 22 Oct 2012 11:37:57 -0400
> Subject: [PATCH 2/2] xen/pvh: Extend vcpu_guest_context, p2m, event, and
> XenBus.
>
> Make gdt_frames[]/gdt_ents into a union with {gdtaddr, gdtsz},
> as PVH only needs to send down gdtaddr and gdtsz in the
> vcpu_guest_context structure..
>
> For interrupts, PVH uses native_irq_ops so we can skip most of the
> PV ones. In the future we can support the pirq_eoi_map..
> Also VCPU hotplug is currently not available for PVH.
>
> For events (and IRQs) we follow what PVHVM does - so use callback
> vector. Lastly, for XenBus we use the same logic that is used in
> the PVHVM case.
>
> Signed-off-by: Mukesh Rathor <mukesh.rathor@...cle.com>
> [v2: Rebased it]
> [v3: Move 64-bit ifdef and based on Stefan add extra comments.]
> 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 | 36 ++++++++++++++++++++++++++-------
> drivers/xen/cpu_hotplug.c | 4 ++-
> drivers/xen/events.c | 9 +++++++-
> drivers/xen/xenbus/xenbus_client.c | 3 +-
> 7 files changed, 56 insertions(+), 14 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 ba49a3a..6f831a1 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();
> }
> @@ -311,7 +314,24 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
>
> memset(&ctxt->fpu_ctxt, 0, sizeof(ctxt->fpu_ctxt));
>
> - {
> + /* check for autoxlated to get it right for 32bit kernel */
> + if (xen_feature(XENFEAT_auto_translated_physmap) &&
> + xen_feature(XENFEAT_supervisor_mode_kernel)) {
> +#ifdef CONFIG_X86_64
> + ctxt->user_regs.ds = __KERNEL_DS;
> + ctxt->user_regs.es = 0;
> + ctxt->user_regs.gs = 0;
> +
> + /* GUEST_GDTR_BASE and */
> + ctxt->u.pvh.gdtaddr = (unsigned long)gdt;
> + /* GUEST_GDTR_LIMIT in the VMCS. */
> + ctxt->u.pvh.gdtsz = (unsigned long)(GDT_SIZE - 1);
> +
> + /* 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;
> diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
> index 4dcfced..de6bcf9 100644
> --- a/drivers/xen/cpu_hotplug.c
> +++ b/drivers/xen/cpu_hotplug.c
> @@ -2,6 +2,7 @@
>
> #include <xen/xen.h>
> #include <xen/xenbus.h>
> +#include <xen/features.h>
>
> #include <asm/xen/hypervisor.h>
> #include <asm/cpu.h>
> @@ -100,7 +101,8 @@ static int __init setup_vcpu_hotplug_event(void)
> static struct notifier_block xsn_cpu = {
> .notifier_call = setup_cpu_watcher };
>
> - if (!xen_pv_domain())
> + /* PVH TBD/FIXME: future work */
> + if (!xen_pv_domain() || xen_feature(XENFEAT_auto_translated_physmap))
> return -ENODEV;
>
> register_xenstore_notifier(&xsn_cpu);
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 59e10a1..7131fdd 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -1774,7 +1774,7 @@ int xen_set_callback_via(uint64_t via)
> }
> EXPORT_SYMBOL_GPL(xen_set_callback_via);
>
> -#ifdef CONFIG_XEN_PVHVM
> +#ifdef CONFIG_X86
> /* Vector callbacks are better than PCI interrupts to receive event
> * channel notifications because we can receive vector callbacks on any
> * vcpu and we don't need PCI support or APIC interactions. */
> @@ -1835,6 +1835,13 @@ void __init xen_init_IRQ(void)
> if (xen_initial_domain())
> pci_xen_initial_domain();
>
> + if (xen_feature(XENFEAT_hvm_callback_vector)) {
> + xen_callback_vector();
> + return;
> + }
> +
> + /* PVH: TBD/FIXME: debug and fix eio map to work with pvh */
> +
> pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> eoi_gmfn.gmfn = virt_to_mfn(pirq_eoi_map);
> rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, &eoi_gmfn);
> diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
> index bcf3ba4..356461e 100644
> --- a/drivers/xen/xenbus/xenbus_client.c
> +++ b/drivers/xen/xenbus/xenbus_client.c
> @@ -44,6 +44,7 @@
> #include <xen/grant_table.h>
> #include <xen/xenbus.h>
> #include <xen/xen.h>
> +#include <xen/features.h>
>
> #include "xenbus_probe.h"
>
> @@ -741,7 +742,7 @@ static const struct xenbus_ring_ops ring_ops_hvm = {
>
> void __init xenbus_ring_ops_init(void)
> {
> - if (xen_pv_domain())
> + if (xen_pv_domain() && !xen_feature(XENFEAT_auto_translated_physmap))
> ring_ops = &ring_ops_pv;
> else
> ring_ops = &ring_ops_hvm;
> --
> 1.7.7.6
>
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