Re: [Xen-devel] [PATCH V3 3/6]: PVH: mmu related changes.

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Thu, 18 Oct 2012 12:31:08 +0100
Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> wrote:

> On Thu, 18 Oct 2012, Mukesh Rathor wrote:
> > PVH: This patch implements mmu changes for PVH. First the set/clear
> > mmio pte function makes a hypercall to update the p2m in xen with
> > 1:1 mapping. PVH uses mostly native mmu ops. Two local functions
> > are introduced to add to xen physmap for xen remap interface. xen
> > unmap interface is introduced so the privcmd pte entries can be
> > cleared in xen p2m table.
> > 
> > Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> > ---
> >  arch/x86/xen/mmu.c    |  174
> > ++++++++++++++++++++++++++++++++++++++++++++++---
> > arch/x86/xen/mmu.h    |    2 + drivers/xen/privcmd.c |    5 +-
> >  include/xen/xen-ops.h |    5 +-
> >  4 files changed, 174 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> > index 5a16824..5ed3b3e 100644
> > --- a/arch/x86/xen/mmu.c
> > +++ b/arch/x86/xen/mmu.c
> > @@ -73,6 +73,7 @@
> >  #include <xen/interface/version.h>
> >  #include <xen/interface/memory.h>
> >  #include <xen/hvc-console.h>
> > +#include <xen/balloon.h>
> >  
> >  #include "multicalls.h"
> >  #include "mmu.h"
> > @@ -331,6 +332,20 @@ static void xen_set_pte(pte_t *ptep, pte_t
> > pteval) __xen_set_pte(ptep, pteval);
> >  }
> >  
> > +void xen_set_clr_mmio_pvh_pte(unsigned long pfn, unsigned long mfn,
> > +                         int nr_mfns, int add_mapping)
> > +{
> > +   struct physdev_map_iomem iomem;
> > +
> > +   iomem.first_gfn = pfn;
> > +   iomem.first_mfn = mfn;
> > +   iomem.nr_mfns = nr_mfns;
> > +   iomem.add_mapping = add_mapping;
> > +
> > +   if (HYPERVISOR_physdev_op(PHYSDEVOP_pvh_map_iomem, &iomem))
> > +           BUG();
> > +}
> 
> You introduce this function here but it is unused. It is not clear
> from the patch description why you are introducing it.
> 
> 
> >  static void xen_set_pte_at(struct mm_struct *mm, unsigned long
> > addr, pte_t *ptep, pte_t pteval)
> >  {
> > @@ -1220,6 +1235,8 @@ static void __init xen_pagetable_init(void)
> >  #endif
> >     paging_init();
> >     xen_setup_shared_info();
> > +   if (xen_feature(XENFEAT_auto_translated_physmap))
> > +           return;
> >  #ifdef CONFIG_X86_64
> >     if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> >             unsigned long new_mfn_list;
> > @@ -1527,6 +1544,10 @@ static void __init xen_set_pte_init(pte_t
> > *ptep, pte_t pte) static void pin_pagetable_pfn(unsigned cmd,
> > unsigned long pfn) {
> >     struct mmuext_op op;
> > +
> > +   if (xen_feature(XENFEAT_writable_page_tables))
> > +           return;
> > +
> >     op.cmd = cmd;
> >     op.arg1.mfn = pfn_to_mfn(pfn);
> >     if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
> > @@ -1724,6 +1745,10 @@ static void set_page_prot(void *addr,
> > pgprot_t prot) unsigned long pfn = __pa(addr) >> PAGE_SHIFT;
> >     pte_t pte = pfn_pte(pfn, prot);
> >  
> > +   /* recall for PVH, page tables are native. */
> > +   if (xen_feature(XENFEAT_auto_translated_physmap))
> > +           return;
> > +
> >     if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte,
> > 0)) BUG();
> >  }
> > @@ -1801,6 +1826,9 @@ static void convert_pfn_mfn(void *v)
> >     pte_t *pte = v;
> >     int i;
> >  
> > +   if (xen_feature(XENFEAT_auto_translated_physmap))
> > +           return;
> > +
> >     /* All levels are converted the same way, so just treat
> > them as ptes. */
> >     for (i = 0; i < PTRS_PER_PTE; i++)
> > @@ -1820,6 +1848,7 @@ static void __init check_pt_base(unsigned
> > long *pt_base, unsigned long *pt_end, (*pt_end)--;
> >     }
> >  }
> > +
> >  /*
> >   * Set up the initial kernel pagetable.
> >   *
> > @@ -1830,6 +1859,7 @@ static void __init check_pt_base(unsigned
> > long *pt_base, unsigned long *pt_end,
> >   * but that's enough to get __va working.  We need to fill in the
> > rest
> >   * of the physical mapping once some sort of allocator has been set
> >   * up.
> > + * NOTE: for PVH, the page tables are native.
> >   */
> >  void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long
> > max_pfn) {
> > @@ -1907,10 +1937,13 @@ void __init
> > xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
> >      * structure to attach it to, so make sure we just set
> > kernel
> >      * pgd.
> >      */
> > -   xen_mc_batch();
> > -   __xen_write_cr3(true, __pa(init_level4_pgt));
> > -   xen_mc_issue(PARAVIRT_LAZY_CPU);
> > -
> > +   if (xen_feature(XENFEAT_writable_page_tables)) {
> > +           native_write_cr3(__pa(init_level4_pgt));
> > +   } else {
> > +           xen_mc_batch();
> > +           __xen_write_cr3(true, __pa(init_level4_pgt));
> > +           xen_mc_issue(PARAVIRT_LAZY_CPU);
> > +   }
> >     /* We can't that easily rip out L3 and L2, as the Xen
> > pagetables are
> >      * set out this way: [L4], [L1], [L2], [L3], [L1],
> > [L1] ...  for
> >      * the initial domain. For guests using the toolstack,
> > they are in: @@ -2177,8 +2210,20 @@ static const struct pv_mmu_ops
> > xen_mmu_ops __initconst = { 
> >  void __init xen_init_mmu_ops(void)
> >  {
> > -   x86_init.mapping.pagetable_reserve =
> > xen_mapping_pagetable_reserve; x86_init.paging.pagetable_init =
> > xen_pagetable_init; +
> > +   if (xen_feature(XENFEAT_auto_translated_physmap)) {
> > +           pv_mmu_ops.flush_tlb_others = xen_flush_tlb_others;
> > +#if 0
> > +           /* For PCI devices to map iomem. */
> > +           if (xen_initial_domain()) {
> > +                   pv_mmu_ops.set_pte = native_set_pte;
> > +                   pv_mmu_ops.set_pte_at = native_set_pte_at;
> > +           }
> > +#endif
> 
> just remove the commented out code

Rats, this got sneaked in! I meant to remove it. I was testing it out
without the code. That if statement has been changing constantly to the
point where it became just native, and could be removed. 


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