> From: Jan Beulich <jbeul...@suse.com>
> Sent: Friday, October 22, 2021 1:59 PM
>
> On 21.10.2021 11:58, Jan Beulich wrote:
> > x2apic_bsp_setup() gets called ahead of iommu_setup(), and since x2APIC
> > mode (physical vs clustered) depends on iommu_intremap, that variable
> > needs to be set to off as soon as we know we can't / won't enable
> > interrupt remapping, i.e. in particular when parsing of the respective
> > ACPI tables failed. Move the turning off of iommu_intremap from AMD
> > specific code into acpi_iommu_init(), accompanying it by clearing of
> > iommu_enable.
> >
> > Take the opportunity and also fully skip ACPI table parsing logic on
> > VT-d when both "iommu=off" and "iommu=no-intremap" are in effect
> anyway,
> > like was already the case for AMD.
> >
> > The tag below only references the commit uncovering a pre-existing
> > anomaly.
> >
> > Fixes: d8bd82327b0f ("AMD/IOMMU: obtain IVHD type to use earlier")
> > Reported-by: Andrew Cooper <andrew.coop...@citrix.com>
> > Signed-off-by: Jan Beulich <jbeul...@suse.com>
>
> Ouch, forgot to Cc Kevin; now added.
Reviewed-by: Kevin Tian <kevin.t...@intel.com>
>
> Jan
>
> > ---
> > While the change here deals with apic_x2apic_probe() as called from
> > x2apic_bsp_setup(), the check_x2apic_preenabled() path looks to be
> > similarly affected. That call occurs before acpi_boot_init(), which is
> > what calls acpi_iommu_init(). The ordering in setup.c is in part
> > relatively fragile, which is why for the moment I'm still hesitant to
> > move the generic_apic_probe() call down. Plus I don't have easy access
> > to a suitable system to test this case. Thoughts?
> > ---
> > v2: Treat iommu_enable and iommu_intremap as separate options.
> >
> > --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
> > +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
> > @@ -183,9 +183,6 @@ int __init acpi_ivrs_init(void)
> > {
> > int rc;
> >
> > - if ( !iommu_enable && !iommu_intremap )
> > - return 0;
> > -
> > rc = amd_iommu_get_supported_ivhd_type();
> > if ( rc < 0 )
> > return rc;
> > @@ -193,10 +190,7 @@ int __init acpi_ivrs_init(void)
> > ivhd_type = rc;
> >
> > if ( (amd_iommu_detect_acpi() !=0) || (iommu_found() == 0) )
> > - {
> > - iommu_intremap = iommu_intremap_off;
> > return -ENODEV;
> > - }
> >
> > iommu_init_ops = &_iommu_init_ops;
> >
> > --- a/xen/drivers/passthrough/vtd/dmar.c
> > +++ b/xen/drivers/passthrough/vtd/dmar.c
> > @@ -777,11 +777,7 @@ static int __init acpi_parse_dmar(struct
> > dmar = (struct acpi_table_dmar *)table;
> > dmar_flags = dmar->flags;
> >
> > - if ( !iommu_enable && !iommu_intremap )
> > - {
> > - ret = -EINVAL;
> > - goto out;
> > - }
> > + ASSERT(iommu_enable || iommu_intremap);
> >
> > if ( !dmar->width )
> > {
> > --- a/xen/drivers/passthrough/x86/iommu.c
> > +++ b/xen/drivers/passthrough/x86/iommu.c
> > @@ -41,6 +41,24 @@ enum iommu_intremap __read_mostly iommu_
> > bool __read_mostly iommu_intpost;
> > #endif
> >
> > +void __init acpi_iommu_init(void)
> > +{
> > + int ret;
> > +
> > + if ( !iommu_enable && !iommu_intremap )
> > + return;
> > +
> > + ret = acpi_dmar_init();
> > + if ( ret == -ENODEV )
> > + ret = acpi_ivrs_init();
> > +
> > + if ( ret )
> > + {
> > + iommu_enable = false;
> > + iommu_intremap = iommu_intremap_off;
> > + }
> > +}
> > +
> > int __init iommu_hardware_setup(void)
> > {
> > struct IO_APIC_route_entry **ioapic_entries = NULL;
> > --- a/xen/include/asm-x86/acpi.h
> > +++ b/xen/include/asm-x86/acpi.h
> > @@ -141,16 +141,10 @@ extern u32 x86_acpiid_to_apicid[];
> > extern u32 pmtmr_ioport;
> > extern unsigned int pmtmr_width;
> >
> > +void acpi_iommu_init(void);
> > int acpi_dmar_init(void);
> > int acpi_ivrs_init(void);
> >
> > -static inline int acpi_iommu_init(void)
> > -{
> > - int ret = acpi_dmar_init();
> > -
> > - return ret == -ENODEV ? acpi_ivrs_init() : ret;
> > -}
> > -
> > void acpi_mmcfg_init(void);
> >
> > /* Incremented whenever we transition through S3. Value is 1 during boot.
> */
> >
> >
