Re: [Xen-devel] [PATCH v1 4/8]: PVH setup changes...

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Fri, Sep 21, 2012 at 12:17:52PM -0700, Mukesh Rathor wrote:
> 
> ---
>  arch/x86/xen/setup.c |   51 ++++++++++++++++++++++++++++++++++++++++++-------
>  1 files changed, 43 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index ead8557..fba442e 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -26,6 +26,7 @@
>  #include <xen/interface/memory.h>
>  #include <xen/interface/physdev.h>
>  #include <xen/features.h>
> +#include "mmu.h"
>  #include "xen-ops.h"
>  #include "vdso.h"
>  
> @@ -222,6 +223,26 @@ static void __init xen_set_identity_and_release_chunk(
>       *identity += set_phys_range_identity(start_pfn, end_pfn);
>  }
>  
> +/* For PVH, the pfns [0..MAX] are mapped to mfn's in the EPT/NPT. The mfns
> + * are released as part of this 1:1 mapping hypercall back to the dom heap. 
> We
> + * don't use the xen_do_chunk() PV does above because when P2M/EPT/NPT is 
> + * updated, the mfns are already lost as part of the p2m update.
> + * Also, we map the entire IO space, ie, beyond max_pfn_mapped.
> + */
> +static void __init xen_pvh_identity_map_chunk(unsigned long start_pfn,
> +             unsigned long end_pfn, unsigned long *released, 
> +             unsigned long *identity)
> +{
> +     unsigned long pfn;
> +     int numpfns=1, add_mapping=1;
> +
> +     for (pfn = start_pfn; pfn < end_pfn; pfn++)
> +             xen_set_clr_mmio_pvh_pte(pfn, pfn, numpfns, add_mapping);
> +
> +     *released += end_pfn - start_pfn;

So this will feed in the populate method that will try to populate back
the amount that were released (xen_populate_chunk). Is that OK? You
mention that we do not want to call 'xen_do_chunk()' but the
'xen_populate_chunk' would do that for XENMEM_populate_physmap call.

The modifcation of *released also ends up modifying the "xen_released_pages"
value which is a global value that the balloon driver ends up using so
we have to be carefull?

Perhaps we should just do this (on top of this patch) for right now:

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 8971a26..3d33ac6 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -103,6 +103,15 @@ static unsigned long __init xen_do_chunk(unsigned long 
start,
        unsigned long pfn;
        int ret;
 
+       if (xen_feature(XENFEAT_auto_translated_physmap)) {
+               /* The xen_set_clr_mmio_pvh_pte did the job for us. */
+               if (release)
+                       return end - start;
+               /* And we do not populate back here.. Meaning that the
+                * later balloon driver can do it based on xen_released_pages.
+                * This will be fixed in the future. */
+               return 0;
+       }
        for (pfn = start; pfn < end; pfn++) {
                unsigned long frame;
                unsigned long mfn = pfn_to_mfn(pfn);


> +     *identity += end_pfn - start_pfn;
> +}
> +
>  static unsigned long __init xen_set_identity_and_release(
>       const struct e820entry *list, size_t map_size, unsigned long nr_pages)
>  {
> @@ -230,6 +251,7 @@ static unsigned long __init xen_set_identity_and_release(
>       unsigned long identity = 0;
>       const struct e820entry *entry;
>       int i;
> +     int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
>  
>       /*
>        * Combine non-RAM regions and gaps until a RAM region (or the
> @@ -251,11 +273,16 @@ static unsigned long __init 
> xen_set_identity_and_release(
>                       if (entry->type == E820_RAM)
>                               end_pfn = PFN_UP(entry->addr);
>  
> -                     if (start_pfn < end_pfn)
> -                             xen_set_identity_and_release_chunk(
> -                                     start_pfn, end_pfn, nr_pages,
> -                                     &released, &identity);
> -
> +                     if (start_pfn < end_pfn) {
> +                             if (xlated_phys) {
> +                                     xen_pvh_identity_map_chunk(start_pfn, 
> +                                             end_pfn, &released, &identity);
> +                             } else {
> +                                     xen_set_identity_and_release_chunk(
> +                                             start_pfn, end_pfn, nr_pages,
> +                                             &released, &identity);

Might as well just move this in the xen_set_identity_and_release_chunk
function. Meaning, leave this function along and just modify
xen_set_identity_and_release_chunk to do the modifications, like this:


diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 8971a26..3db3f46 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -103,6 +103,15 @@ static unsigned long __init xen_do_chunk(unsigned long 
start,
        unsigned long pfn;
        int ret;
 
+       if (xen_feature(XENFEAT_auto_translated_physmap)) {
+               /* The xen_set_clr_mmio_pvh_pte did the job for us. */
+               if (release)
+                       return end - start;
+               /* And we do not populate back here.. Meaning that the
+                * later balloon driver can do it based on xen_released_pages.
+                * This will be fixed in the future. */
+               return 0;
+       }
        for (pfn = start; pfn < end; pfn++) {
                unsigned long frame;
                unsigned long mfn = pfn_to_mfn(pfn);
@@ -218,11 +227,15 @@ static void __init xen_set_identity_and_release_chunk(
         * If the PFNs are currently mapped, the VA mapping also needs
         * to be updated to be 1:1.
         */
-       for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
-               (void)HYPERVISOR_update_va_mapping(
-                       (unsigned long)__va(pfn << PAGE_SHIFT),
-                       mfn_pte(pfn, PAGE_KERNEL_IO), 0);
-
+       for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++) {
+               if (xen_feature(XENFEAT_auto_translated_physmap)) {
+                       xen_set_clr_mmio_pvh_pte(pfn, pfn, 1, 1);
+               } else {
+                       (void)HYPERVISOR_update_va_mapping(
+                               (unsigned long)__va(pfn << PAGE_SHIFT),
+                               mfn_pte(pfn, PAGE_KERNEL_IO), 0);
+               }
+       }
        if (start_pfn < nr_pages)
                *released += xen_release_chunk(
                        start_pfn, min(end_pfn, nr_pages));
> +                             }
> +                     }
>                       start = end;
>               }
>       }
> @@ -500,10 +527,9 @@ void __cpuinit xen_enable_syscall(void)
>  #endif /* CONFIG_X86_64 */
>  }
>  
> -void __init xen_arch_setup(void)
> +/* Non auto translated PV domain, ie, it's not PVH. */
> +static __init void inline xen_non_pvh_arch_setup(void)
>  {
> -     xen_panic_handler_init();
> -
>       HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments);
>       HYPERVISOR_vm_assist(VMASST_CMD_enable, 
> VMASST_TYPE_writable_pagetables);
>  
> @@ -517,6 +543,15 @@ void __init xen_arch_setup(void)
>  
>       xen_enable_sysenter();
>       xen_enable_syscall();
> +}
> +
> +/* This function not called for HVM domain */
> +void __init xen_arch_setup(void)
> +{
> +     xen_panic_handler_init();
> +
> +     if (!xen_feature(XENFEAT_auto_translated_physmap))
> +             xen_non_pvh_arch_setup();
>  

I am not sure what the syscall functions have to do with parsing of the
E820.

You should split this patch in two - one that deals with the E820
parsing and another that deails with the setup of syscalls.

>  #ifdef CONFIG_ACPI
>       if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
> -- 
> 1.7.2.3
> 
> 
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> 

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