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

[Yuke Peng]

Hi

On Sun, Jul 21, 2024 at 3:05 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> 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?

Sorry for the late reply and for not using the "reply to all" option.
I will update the reply email:

On Fri, Jul 12, 2024 at 2:56 AM CLEMENT MATHIEU--DRIF
<clement.mathieu--drif@eviden.com> wrote:
>
> On 11/07/2024 10:19, Yuke Peng wrote:
> >
> > On Tue, Jul 9, 2024 at 12:43 PM CLEMENT MATHIEU--DRIF 
> > <clement.mathieu--drif@eviden.com> wrote:
> > >
> > > Hi
> > >
> > > On 08/07/2024 12:08, Yuke Peng wrote:
> > > > +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?
> > >
> >
> > When I attempted to use vtd_vmstate as a reference to name the
> > cfi subsection. I found the proposed name was a bit odd for me, like
> > "vtd_cfi_vmstate" or "vtd_vmstate_cfi".
> >
> > I checked the other examples using subsections and I found they use
> > vmstate_xxx like "vmstate_serial" and "vmstate_serial_timeout_ipending".
> > So here I rename vtd_vmstate to vmstate_vtd.
>
> Hi,
>
> I can't say if this will be approved or not.
> But if you really think renaming is important, you should make a patch for 
> that specific change instead of using the same patch for all changes.
>
> Maybe you should consider using "reply all" so that people on the list can 
> keep track of the conversation.

I had intended to split this patch into two parts, but I've been too
busy to work on it. I'm sorry about that.

>
>
> > >       .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
> > >
> > >
>

Yuke Peng