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

[CLEMENT MATHIEU--DRIF]

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?
>       .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
>
>