Re: [PATCH v2] hw/i386/intel_iommu: Block CFI when necessary

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jul 09, 2024 at 04:43:25AM +0000, CLEMENT MATHIEU--DRIF wrote:
> Hi
> 
> On 08/07/2024 12:08, Yuke Peng wrote:
> > Caution: External email. Do not open attachments or click links, unless this email comes from a known sender and you know the content is safe.
> >
> >
> > According to Intel VT-d specification 5.1.4, CFI must be blocked when
> > Extended Interrupt Mode is enabled or Compatibility format interrupts
> > are disabled.
> >
> > Signed-off-by: Yuke Peng <pykfirst@gmail.com>
> > ---
> > Changes in v2:
> > - Use subsections for the cfi_enabled field.
> > - Link to v1: https://lore.kernel.org/qemu-devel/20240625112819.862282-1-pykfirst@gmail.com/
> >
> > ---
> >   hw/i386/intel_iommu.c         | 53 +++++++++++++++++++++++++++++++++--
> >   hw/i386/trace-events          |  1 +
> >   include/hw/i386/intel_iommu.h |  1 +
> >   3 files changed, 53 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> > index 5085a6fee3..af9c864bde 100644
> > --- a/hw/i386/intel_iommu.c
> > +++ b/hw/i386/intel_iommu.c
> > @@ -2410,6 +2410,22 @@ static void vtd_handle_gcmd_ire(IntelIOMMUState *s, bool en)
> >       }
> >   }
> >
> > +/* Handle Compatibility Format Interrupts Enable/Disable */
> > +static void vtd_handle_gcmd_cfi(IntelIOMMUState *s, bool en)
> > +{
> > +    trace_vtd_cfi_enable(en);
> > +
> > +    if (en) {
> > +        s->cfi_enabled = true;
> > +        /* Ok - report back to driver */
> > +        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_CFIS);
> > +    } else {
> > +        s->cfi_enabled = false;
> > +        /* Ok - report back to driver */
> > +        vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_CFIS, 0);
> > +    }
> > +}
> > +
> >   /* Handle write to Global Command Register */
> >   static void vtd_handle_gcmd_write(IntelIOMMUState *s)
> >   {
> > @@ -2440,6 +2456,10 @@ static void vtd_handle_gcmd_write(IntelIOMMUState *s)
> >           /* Interrupt remap enable/disable */
> >           vtd_handle_gcmd_ire(s, val & VTD_GCMD_IRE);
> >       }
> > +    if (changed & VTD_GCMD_CFI) {
> > +        /* Compatibility format interrupts enable/disable */
> > +        vtd_handle_gcmd_cfi(s, val & VTD_GCMD_CFI);
> > +    }
> >   }
> >
> >   /* Handle write to Context Command Register */
> > @@ -3283,7 +3303,25 @@ static int vtd_post_load(void *opaque, int version_id)
> >       return 0;
> >   }
> >
> > -static const VMStateDescription vtd_vmstate = {
> > +static bool vtd_cfi_needed(void *opaque)
> > +{
> > +    IntelIOMMUState *iommu = opaque;
> > +
> > +    return iommu->intr_enabled && !iommu->intr_eime;
> > +}
> > +
> > +static const VMStateDescription vmstate_vtd_cfi = {
> > +    .name = "iommu-intel/cfi",
> > +    .version_id = 1,
> > +    .minimum_version_id = 1,
> > +    .needed = vtd_cfi_needed,
> > +    .fields = (VMStateField[]) {
> > +        VMSTATE_BOOL(cfi_enabled, IntelIOMMUState),
> > +        VMSTATE_END_OF_LIST()
> > +    }
> > +};
> > +
> > +static const VMStateDescription vmstate_vtd = {
> Why is vtd_vmstate renamed to vmstate_vtd? is it necessary?



Yuke Peng, do you plan to answer this?

> >       .name = "iommu-intel",
> >       .version_id = 1,
> >       .minimum_version_id = 1,
> > @@ -3306,6 +3344,10 @@ static const VMStateDescription vtd_vmstate = {
> >           VMSTATE_BOOL(intr_enabled, IntelIOMMUState),
> >           VMSTATE_BOOL(intr_eime, IntelIOMMUState),
> >           VMSTATE_END_OF_LIST()
> > +    },
> > +    .subsections = (const VMStateDescription * []) {
> > +        &vmstate_vtd_cfi,
> > +        NULL
> >       }
> >   };
> >
> > @@ -3525,6 +3567,12 @@ static int vtd_interrupt_remap_msi(IntelIOMMUState *iommu,
> >
> >       /* This is compatible mode. */
> >       if (addr.addr.int_mode != VTD_IR_INT_FORMAT_REMAP) {
> > +        if (iommu->intr_eime || !iommu->cfi_enabled) {
> > +            if (do_fault) {
> > +                vtd_report_ir_fault(iommu, sid, VTD_FR_IR_REQ_COMPAT, 0);
> > +            }
> > +            return -EINVAL;
> > +        }
> >           memcpy(translated, origin, sizeof(*origin));
> >           goto out;
> >       }
> > @@ -3950,6 +3998,7 @@ static void vtd_init(IntelIOMMUState *s)
> >       s->root_scalable = false;
> >       s->dmar_enabled = false;
> >       s->intr_enabled = false;
> > +    s->cfi_enabled = false;
> >       s->iq_head = 0;
> >       s->iq_tail = 0;
> >       s->iq = 0;
> > @@ -4243,7 +4292,7 @@ static void vtd_class_init(ObjectClass *klass, void *data)
> >       X86IOMMUClass *x86_class = X86_IOMMU_DEVICE_CLASS(klass);
> >
> >       dc->reset = vtd_reset;
> > -    dc->vmsd = &vtd_vmstate;
> > +    dc->vmsd = &vmstate_vtd;
> >       device_class_set_props(dc, vtd_properties);
> >       dc->hotpluggable = false;
> >       x86_class->realize = vtd_realize;
> > diff --git a/hw/i386/trace-events b/hw/i386/trace-events
> > index 53c02d7ac8..ffd87db65f 100644
> > --- a/hw/i386/trace-events
> > +++ b/hw/i386/trace-events
> > @@ -57,6 +57,7 @@ vtd_dmar_translate(uint8_t bus, uint8_t slot, uint8_t func, uint64_t iova, uint6
> >   vtd_dmar_enable(bool en) "enable %d"
> >   vtd_dmar_fault(uint16_t sid, int fault, uint64_t addr, bool is_write) "sid 0x%"PRIx16" fault %d addr 0x%"PRIx64" write %d"
> >   vtd_ir_enable(bool en) "enable %d"
> > +vtd_cfi_enable(bool en) "enable %d"
> >   vtd_ir_irte_get(int index, uint64_t lo, uint64_t hi) "index %d low 0x%"PRIx64" high 0x%"PRIx64
> >   vtd_ir_remap(int index, int tri, int vec, int deliver, uint32_t dest, int dest_mode) "index %d trigger %d vector %d deliver %d dest 0x%"PRIx32" mode %d"
> >   vtd_ir_remap_type(const char *type) "%s"
> > diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
> > index 7fa0a695c8..38e20d0f2c 100644
> > --- a/include/hw/i386/intel_iommu.h
> > +++ b/include/hw/i386/intel_iommu.h
> > @@ -294,6 +294,7 @@ struct IntelIOMMUState {
> >
> >       /* interrupt remapping */
> >       bool intr_enabled;              /* Whether guest enabled IR */
> > +    bool cfi_enabled;               /* Whether CFI is enabled */
> >       dma_addr_t intr_root;           /* Interrupt remapping table pointer */
> >       uint32_t intr_size;             /* Number of IR table entries */
> >       bool intr_eime;                 /* Extended interrupt mode enabled */
> > --
> > 2.34.1
> >
> >