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Re: [Xen-devel] fixed location of share info page in HVM guests



>>> On 23.10.12 at 21:49, Olaf Hering <olaf@xxxxxxxxx> wrote:
> The open question is when to switch from early_ioremap to
> ioremap. Then the change to drivers/xen/platform-pci.c can be removed.

Wouldn't you be better of using
early_set_fixmap(FIX_PARAVIRT_BOOTMAP, ...) anyway? If not,
mm_init() (due to its calling of vmalloc_init()) would be the apparent
boundary between using early and normal ioremaps.

>  xen PVonHVM: move shared_info to reserved memory area
> 
> ---
>  arch/x86/include/asm/xen/hypervisor.h |  2 ++
>  arch/x86/xen/enlighten.c              | 53 
> ++++++++++++++++++++++++++---------
>  arch/x86/xen/suspend.c                |  2 +-
>  arch/x86/xen/xen-ops.h                |  2 +-
>  drivers/xen/platform-pci.c            |  2 ++
>  include/xen/events.h                  |  2 ++
>  6 files changed, 48 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/include/asm/xen/hypervisor.h 
> b/arch/x86/include/asm/xen/hypervisor.h
> index 66d0fff..e29a02b 100644
> --- a/arch/x86/include/asm/xen/hypervisor.h
> +++ b/arch/x86/include/asm/xen/hypervisor.h
> @@ -34,6 +34,8 @@
>  #define _ASM_X86_XEN_HYPERVISOR_H
>  
>  /* arch/i386/kernel/setup.c */
> +#define HVM_SHARED_INFO_ADDR 0xFE700000UL
> +
>  extern struct shared_info *HYPERVISOR_shared_info;
>  extern struct start_info *xen_start_info;
>  
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index e3497f2..b051c3f 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -103,7 +103,6 @@ struct shared_info xen_dummy_shared_info;
>  
>  void *xen_initial_gdt;
>  
> -RESERVE_BRK(shared_info_page_brk, PAGE_SIZE);
>  __read_mostly int xen_have_vector_callback;
>  EXPORT_SYMBOL_GPL(xen_have_vector_callback);
>  
> @@ -1497,38 +1496,66 @@ asmlinkage void __init xen_start_kernel(void)
>  #endif
>  }
>  
> -void __ref xen_hvm_init_shared_info(void)
> +#ifdef CONFIG_XEN_PVHVM
> +static struct shared_info *xen_hvm_shared_info;
> +
> +static void xen_hvm_connect_shared_info(unsigned long pfn)
>  {
> -     int cpu;
>       struct xen_add_to_physmap xatp;
> -     static struct shared_info *shared_info_page = 0;
>  
> -     if (!shared_info_page)
> -             shared_info_page = (struct shared_info *)
> -                     extend_brk(PAGE_SIZE, PAGE_SIZE);
>       xatp.domid = DOMID_SELF;
>       xatp.idx = 0;
>       xatp.space = XENMAPSPACE_shared_info;
> -     xatp.gpfn = __pa(shared_info_page) >> PAGE_SHIFT;
> +     xatp.gpfn = pfn;
>       if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
>               BUG();
>  
> -     HYPERVISOR_shared_info = (struct shared_info *)shared_info_page;
> +}
> +static void xen_hvm_set_shared_info(struct shared_info *sip)
> +{
> +     int cpu;
> +
> +     HYPERVISOR_shared_info = sip;
>  
>       /* xen_vcpu is a pointer to the vcpu_info struct in the shared_info
>        * page, we use it in the event channel upcall and in some pvclock
>        * related functions. We don't need the vcpu_info placement
>        * optimizations because we don't use any pv_mmu or pv_irq op on
>        * HVM.
> -      * When xen_hvm_init_shared_info is run at boot time only vcpu 0 is
> -      * online but xen_hvm_init_shared_info is run at resume time too and
> +      * When xen_hvm_set_shared_info is run at boot time only vcpu 0 is
> +      * online but xen_hvm_set_shared_info is run at resume time too and
>        * in that case multiple vcpus might be online. */
>       for_each_online_cpu(cpu) {
>               per_cpu(xen_vcpu, cpu) = 
> &HYPERVISOR_shared_info->vcpu_info[cpu];
>       }
>  }
>  
> -#ifdef CONFIG_XEN_PVHVM
> +/* Reconnect the shared_info pfn to a (new) mfn */
> +void xen_hvm_resume_shared_info(void)
> +{
> +     xen_hvm_connect_shared_info(HVM_SHARED_INFO_ADDR >> PAGE_SHIFT);
> +}
> +
> +/* Update shared_info address */
> +void __devinit xen_hvm_init_shared_info(void)
> +{
> +     struct shared_info *early;
> +
> +     early = xen_hvm_shared_info;
> +     xen_hvm_shared_info = ioremap(HVM_SHARED_INFO_ADDR, PAGE_SIZE);
> +     xen_hvm_set_shared_info(xen_hvm_shared_info);
> +     wmb();
> +     early_iounmap(early, PAGE_SIZE);

This is a call from __devinit to __init, which isn't allowed. And I'm
pretty sure it's too late to do this here anyway.

Jan

> +}
> +
> +/* Obtain an address to the pfn in reserved area */
> +static void __init xen_hvm_early_init_shared_info(void)
> +{
> +     xen_hvm_shared_info = early_ioremap(HVM_SHARED_INFO_ADDR, PAGE_SIZE);
> +     xen_hvm_connect_shared_info(HVM_SHARED_INFO_ADDR >> PAGE_SHIFT);
> +     xen_hvm_set_shared_info(xen_hvm_shared_info);
> +}
> +
>  static void __init init_hvm_pv_info(void)
>  {
>       int major, minor;
> @@ -1578,7 +1605,7 @@ static void __init xen_hvm_guest_init(void)
>  {
>       init_hvm_pv_info();
>  
> -     xen_hvm_init_shared_info();
> +     xen_hvm_early_init_shared_info();
>  
>       if (xen_feature(XENFEAT_hvm_callback_vector))
>               xen_have_vector_callback = 1;
> diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
> index 45329c8..ae8a00c 100644
> --- a/arch/x86/xen/suspend.c
> +++ b/arch/x86/xen/suspend.c
> @@ -30,7 +30,7 @@ void xen_arch_hvm_post_suspend(int suspend_cancelled)
>  {
>  #ifdef CONFIG_XEN_PVHVM
>       int cpu;
> -     xen_hvm_init_shared_info();
> +     xen_hvm_resume_shared_info();
>       xen_callback_vector();
>       xen_unplug_emulated_devices();
>       if (xen_feature(XENFEAT_hvm_safe_pvclock)) {
> diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
> index a95b417..d2e73d1 100644
> --- a/arch/x86/xen/xen-ops.h
> +++ b/arch/x86/xen/xen-ops.h
> @@ -40,7 +40,7 @@ void xen_enable_syscall(void);
>  void xen_vcpu_restore(void);
>  
>  void xen_callback_vector(void);
> -void xen_hvm_init_shared_info(void);
> +void xen_hvm_resume_shared_info(void);
>  void xen_unplug_emulated_devices(void);
>  
>  void __init xen_build_dynamic_phys_to_machine(void);
> diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
> index 97ca359..989365f 100644
> --- a/drivers/xen/platform-pci.c
> +++ b/drivers/xen/platform-pci.c
> @@ -138,6 +138,8 @@ static int __devinit platform_pci_init(struct pci_dev 
> *pdev,
>       platform_mmio = mmio_addr;
>       platform_mmiolen = mmio_len;
>  
> +     xen_hvm_init_shared_info();
> +
>       if (!xen_have_vector_callback) {
>               ret = xen_allocate_irq(pdev);
>               if (ret) {
> diff --git a/include/xen/events.h b/include/xen/events.h
> index c6bfe01..58c8431 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -58,6 +58,8 @@ void notify_remote_via_irq(int irq);
>  
>  void xen_irq_resume(void);
>  
> +void xen_hvm_init_shared_info(void);
> +
>  /* Clear an irq's pending state, in preparation for polling on it */
>  void xen_clear_irq_pending(int irq);
>  void xen_set_irq_pending(int irq);
> -- 
> 1.7.12.4
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx 
> http://lists.xen.org/xen-devel 



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