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Re: [Xen-devel] [PATCH 4/6] xen/pvh: bootup and setup related changes.



On Mon, Oct 22, 2012 at 02:34:44PM +0100, Stefano Stabellini wrote:
> On Sat, 20 Oct 2012, Konrad Rzeszutek Wilk wrote:
> > From: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> > 
> > In enlighten.c for PVH we can trap cpuid via vmexit, so don't
> > need to use emulated prefix call. We also check for vector callback
> > early on, as it is a required feature. PVH also runs at default kernel
> > IOPL.
> > 
> > In setup.c, in xen_add_extra_mem() we can skip updating P2M as it's managed
> > by Xen. PVH maps the entire IO space, but only RAM pages need to be 
> > repopulated.
> > 
> > Finally, pure PV settings are moved to a separate function that is only 
> > called
> > for pure PV, ie, pv with pvmmu.
> > 
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> >
> > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> > index 8971a26..8cce47b 100644
> > --- a/arch/x86/xen/setup.c
> > +++ b/arch/x86/xen/setup.c
> > @@ -27,6 +27,7 @@
> >  #include <xen/interface/memory.h>
> >  #include <xen/interface/physdev.h>
> >  #include <xen/features.h>
> > +#include "mmu.h"
> >  #include "xen-ops.h"
> >  #include "vdso.h"
> >  
> > @@ -78,6 +79,9 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
> >  
> >     memblock_reserve(start, size);
> >  
> > +   if (xen_feature(XENFEAT_auto_translated_physmap))
> > +           return;
> > +
> >     xen_max_p2m_pfn = PFN_DOWN(start + size);
> >     for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
> >             unsigned long mfn = pfn_to_mfn(pfn);
> > @@ -100,6 +104,7 @@ static unsigned long __init xen_do_chunk(unsigned long 
> > start,
> >             .domid        = DOMID_SELF
> >     };
> >     unsigned long len = 0;
> > +   int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
> >     unsigned long pfn;
> >     int ret;
> >  
> > @@ -113,7 +118,7 @@ static unsigned long __init xen_do_chunk(unsigned long 
> > start,
> >                             continue;
> >                     frame = mfn;
> >             } else {
> > -                   if (mfn != INVALID_P2M_ENTRY)
> > +                   if (!xlated_phys && mfn != INVALID_P2M_ENTRY)
> >                             continue;
> >                     frame = pfn;
> >             }
> 
> Shouldn't we add a "!xlated_phys &&" to the other case as well?

No. That is handled in xen_pvh_identity_map_chunk which
just does a xen_set_clr_mmio_pvh_pte call for the "released"
pages. But that is a bit of ... well, extra logic. I think
if we did this it would work and look much nicer:


diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 8cce47b..b451a77 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -114,9 +114,15 @@ static unsigned long __init xen_do_chunk(unsigned long 
start,
 
                if (release) {
                        /* Make sure pfn exists to start with */
-                       if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
+                       if (mfn == INVALID_P2M_ENTRY || (!xlated_phys && 
(mfn_to_pfn(mfn) != pfn)))
                                continue;
                        frame = mfn;
+                       /* The hypercall PHYSDEVOP_map_iomem to release memory 
has already
+                        * happend, so we just do a nop here. */
+                       if (xlated_phys) {
+                               len++;
+                               continue;
+                       }
                } else {
                        if (!xlated_phys && mfn != INVALID_P2M_ENTRY)
                                continue;
@@ -219,15 +225,24 @@ static void __init xen_set_identity_and_release_chunk(
 {
        unsigned long 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.
+        * Also, we map the entire IO space, ie, beyond max_pfn_mapped.
+        */
+       int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
+
        /*
         * 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 (xlated_phys)
+                       xen_set_clr_mmio_pvh_pte(pfn, pfn, 1 /* one pfn */, 1 
/* add mapping */);
+               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));
@@ -235,27 +250,6 @@ 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.
- * 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 max_pfn)
-{
-       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);
-
-       if (start_pfn <= max_pfn) {
-               unsigned long end = min(max_pfn_mapped, end_pfn);
-               *released += end - start_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)
 {
@@ -286,17 +280,10 @@ 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) {
-                               if (xlated_phys) {
-                                       xen_pvh_identity_map_chunk(start_pfn,
-                                               end_pfn, &released, &identity,
-                                               nr_pages);
-                               } else {
-                                       xen_set_identity_and_release_chunk(
+                       if (start_pfn < end_pfn)
+                               xen_set_identity_and_release_chunk(
                                                start_pfn, end_pfn, nr_pages,
                                                &released, &identity);
-                               }
-                       }
                        start = end;
                }
        }


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