[Xen-devel] Re: [PATCH V2 4/4] amd iommu: interfaces for p2m sharing

[Wei Wang2 <wei.wang2@xxxxxxx>]

On Monday 18 April 2011 12:26:36 Tim Deegan wrote:
> At 13:14 +0100 on 15 Apr (1302873244), Wei Wang2 wrote:
> > --
> > Advanced Micro Devices GmbH
> > Sitz: Dornach, Gemeinde Aschheim,
> > Landkreis München Registergericht München,
> > HRB Nr. 43632
> > WEEE-Reg-Nr: DE 12919551
> > Geschäftsführer:
> > Alberto Bozzo, Andrew Bowd
> >
> > # HG changeset patch
> > # User Wei Wang <wei.wang2@xxxxxxx>
> > # Node ID b5c197b1d2ac80881d0683cdadf12ac33b762614
> > # Parent  1d9b0e45566ec3cd0e293212d9a454920116b2b1
> > Add a generic interface for both vtd and amd iommu p2m sharing. Also
> > introduce a new parameter (iommu=sharept) to enable this feature.
>
> Why does this introduce a separate variable?  Surely "iommu=sharept"
> should just set iommu_hap_pt_share directly.  Also, it looks like
> "iommu=sharept" has different semantics on AMD and Intel machines
> (i.e., it does nothing on Intel). Was that the intention?
Hi Tim
True, that is a little weird.. It looks like some vtd systems have compatible 
issue of re-using p2m table for iommu, so vtd code only turns 
iommu_hap_pt_share on after some compatible checks (in vtd_ept_share). To 
avoid breaking vtd, I intended to keep this in the new code. But your 
suggestion also looks good to me. We could set iommu_hap_pt_share directly 
and turn it off if vtd_ept_share() fails. New patch has been attached.

> The rest of this series looks OK to me.  Is it safe to apply the rest
> without this patch or should I wait for the next version and apply them
> all together?
Yes, it should be OK to just apply the rest. Without the last one, p2m sharing 
will not been enabled.
Thanks,
Wei


> Cheers,
>
> Tim.
>
> > Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
> >
> > diff -r 1d9b0e45566e -r b5c197b1d2ac xen/arch/x86/mm/p2m.c
> > --- a/xen/arch/x86/mm/p2m.c Fri Apr 15 12:10:39 2011 +0200
> > +++ b/xen/arch/x86/mm/p2m.c Fri Apr 15 12:13:24 2011 +0200
> > @@ -2061,8 +2061,8 @@ int p2m_alloc_table(struct p2m_domain *p
> >
> >      p2m->phys_table = pagetable_from_mfn(page_to_mfn(p2m_top));
> >
> > -    if ( hap_enabled(d) && (boot_cpu_data.x86_vendor ==
> > X86_VENDOR_INTEL) ) -        iommu_set_pgd(d);
> > +    if ( hap_enabled(d) )
> > +        iommu_share_p2m_table(d);
> >
> >      P2M_PRINTK("populating p2m table\n");
> >
> > diff -r 1d9b0e45566e -r b5c197b1d2ac
> > xen/drivers/passthrough/amd/iommu_map.c ---
> > a/xen/drivers/passthrough/amd/iommu_map.c   Fri Apr 15 12:10:39 2011 +0200
> > +++ b/xen/drivers/passthrough/amd/iommu_map.c       Fri Apr 15 12:13:24 2011
> > +0200 @@ -716,6 +716,12 @@ void amd_iommu_share_p2m(struct domain *
> >
> >      ASSERT( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled );
> >
> > +    if ( !iommu_sharept )
> > +    {
> > +        iommu_hap_pt_share = 0;
> > +        return;
> > +    }
> > +
> >      pgd_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m_get_hostp2m(d)));
> >      p2m_table = mfn_to_page(mfn_x(pgd_mfn));
> >
> > diff -r 1d9b0e45566e -r b5c197b1d2ac
> > xen/drivers/passthrough/amd/pci_amd_iommu.c ---
> > a/xen/drivers/passthrough/amd/pci_amd_iommu.c       Fri Apr 15 12:10:39 2011
> > +0200 +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c     Fri Apr 15
> > 12:13:24 2011 +0200 @@ -458,4 +458,5 @@ const struct iommu_ops
> > amd_iommu_ops = {
> >      .read_msi_from_ire = amd_iommu_read_msi_from_ire,
> >      .suspend = amd_iommu_suspend,
> >      .resume = amd_iommu_resume,
> > +    .share_p2m = amd_iommu_share_p2m,
> >  };
> > diff -r 1d9b0e45566e -r b5c197b1d2ac xen/drivers/passthrough/iommu.c
> > --- a/xen/drivers/passthrough/iommu.c       Fri Apr 15 12:10:39 2011 +0200
> > +++ b/xen/drivers/passthrough/iommu.c       Fri Apr 15 12:13:24 2011 +0200
> > @@ -50,6 +50,7 @@ bool_t __read_mostly iommu_hap_pt_share;
> >  bool_t __read_mostly iommu_hap_pt_share;
> >  bool_t __read_mostly amd_iommu_debug;
> >  bool_t __read_mostly amd_iommu_perdev_intremap;
> > +bool_t __read_mostly iommu_sharept;
> >
> >  static void __init parse_iommu_param(char *s)
> >  {
> > @@ -82,6 +83,8 @@ static void __init parse_iommu_param(cha
> >              iommu_passthrough = 1;
> >          else if ( !strcmp(s, "dom0-strict") )
> >              iommu_dom0_strict = 1;
> > +        else if ( !strcmp(s, "sharept") )
> > +            iommu_sharept = 1;
> >
> >          s = ss + 1;
> >      } while ( ss );
> > @@ -419,6 +422,14 @@ void iommu_suspend()
> >          ops->suspend();
> >  }
> >
> > +void iommu_share_p2m_table(struct domain* d)
> > +{
> > +    const struct iommu_ops *ops = iommu_get_ops();
> > +
> > +    if ( iommu_enabled && is_hvm_domain(d) )
> > +        ops->share_p2m(d);
> > +}
> > +
> >  /*
> >   * Local variables:
> >   * mode: C
> > diff -r 1d9b0e45566e -r b5c197b1d2ac xen/drivers/passthrough/vtd/iommu.c
> > --- a/xen/drivers/passthrough/vtd/iommu.c   Fri Apr 15 12:10:39 2011 +0200
> > +++ b/xen/drivers/passthrough/vtd/iommu.c   Fri Apr 15 12:13:24 2011 +0200
> > @@ -1747,7 +1747,7 @@ static bool_t vtd_ept_share(void)
> >      bool_t share = TRUE;
> >
> >      /* sharept defaults to 0 for now, default to 1 when feature matures
> > */ -    if ( !sharept )
> > +    if ( !iommu_sharept )
> >          share = FALSE;
> >
> >      /*
> > @@ -2299,6 +2299,7 @@ const struct iommu_ops intel_iommu_ops =
> >      .read_msi_from_ire = msi_msg_read_remap_rte,
> >      .suspend = vtd_suspend,
> >      .resume = vtd_resume,
> > +    .share_p2m = iommu_set_pgd,
> >  };
> >
> >  /*
> > diff -r 1d9b0e45566e -r b5c197b1d2ac xen/include/xen/iommu.h
> > --- a/xen/include/xen/iommu.h       Fri Apr 15 12:10:39 2011 +0200
> > +++ b/xen/include/xen/iommu.h       Fri Apr 15 12:13:24 2011 +0200
> > @@ -33,6 +33,7 @@ extern bool_t iommu_hap_pt_share;
> >  extern bool_t iommu_hap_pt_share;
> >  extern bool_t amd_iommu_debug;
> >  extern bool_t amd_iommu_perdev_intremap;
> > +extern bool_t iommu_sharept;
> >
> >  extern struct rangeset *mmio_ro_ranges;
> >
> > @@ -132,6 +133,7 @@ struct iommu_ops {
> >      unsigned int (*read_apic_from_ire)(unsigned int apic, unsigned int
> > reg); void (*suspend)(void);
> >      void (*resume)(void);
> > +    void (*share_p2m)(struct domain *d);
> >  };
> >
> >  void iommu_update_ire_from_apic(unsigned int apic, unsigned int reg,
> > unsigned int value); @@ -143,5 +145,6 @@ void iommu_resume(void);
> >  void iommu_resume(void);
> >
> >  void iommu_set_dom0_mapping(struct domain *d);
> > +void iommu_share_p2m_table(struct domain *d);
> >
> >  #endif /* _IOMMU_H_ */

Attachment: amd_iommu_p2m_4_new.patch
Description: amd_iommu_p2m_4_new.patch

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