>-----Original Message-----
>From: CLEMENT MATHIEU--DRIF <clement.mathieu--d...@eviden.com>
>Subject: Re: [PATCH v3 03/17] intel_iommu: Add a placeholder variable for
>scalable modern mode
>
>
>
>On 11/09/2024 07:22, Zhenzhong Duan 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.
>>
>>
>> Add an new element scalable_mode in IntelIOMMUState to mark scalable
>> modern mode, this element will be exposed as an intel_iommu property
>> finally.
>>
>> For now, it's only a placehholder and used for address width
>> compatibility check and block host device passthrough until nesting
>> is supported.
>>
>> Signed-off-by: Yi Liu <yi.l....@intel.com>
>> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
>> ---
>> include/hw/i386/intel_iommu.h | 1 +
>> hw/i386/intel_iommu.c | 22 ++++++++++++++++++----
>> 2 files changed, 19 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/hw/i386/intel_iommu.h
>b/include/hw/i386/intel_iommu.h
>> index 1eb05c29fc..788ed42477 100644
>> --- a/include/hw/i386/intel_iommu.h
>> +++ b/include/hw/i386/intel_iommu.h
>> @@ -262,6 +262,7 @@ struct IntelIOMMUState {
>>
>> bool caching_mode; /* RO - is cap CM enabled? */
>> bool scalable_mode; /* RO - is Scalable Mode supported? */
>> + bool scalable_modern; /* RO - is modern SM supported? */
>> bool snoop_control; /* RO - is SNP filed supported? */
>>
>> dma_addr_t root; /* Current root table pointer */
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index e3465fc27d..57c24f67b4 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -3872,7 +3872,13 @@ static bool vtd_check_hiod(IntelIOMMUState
>*s, HostIOMMUDevice *hiod,
>> return false;
>> }
>>
>> - return true;
>> + if (!s->scalable_modern) {
>> + /* All checks requested by VTD non-modern mode pass */
>> + return true;
>> + }
>> +
>> + error_setg(errp, "host device is unsupported in scalable modern mode
>yet");
>> + return false;
>> }
>>
>> static bool vtd_dev_set_iommu_device(PCIBus *bus, void *opaque, int
>devfn,
>> @@ -4262,14 +4268,22 @@ static bool
>vtd_decide_config(IntelIOMMUState *s, Error **errp)
>> }
>> }
>>
>> - /* Currently only address widths supported are 39 and 48 bits */
>> if ((s->aw_bits != VTD_HOST_AW_39BIT) &&
>> - (s->aw_bits != VTD_HOST_AW_48BIT)) {
>> - error_setg(errp, "Supported values for aw-bits are: %d, %d",
>> + (s->aw_bits != VTD_HOST_AW_48BIT) &&
>> + !s->scalable_modern) {
>> + error_setg(errp, "%s mode: supported values for aw-bits
>are: %d, %d",
>> + s->scalable_mode ? "Scalable legacy" : "Legacy",
>I think we should be consistent in the way we name things.
>s/Scalable legacy/Scalable
Will do.
>> VTD_HOST_AW_39BIT, VTD_HOST_AW_48BIT);
>> return false;
>> }
>>
>> + if ((s->aw_bits != VTD_HOST_AW_48BIT) && s->scalable_modern) {
>> + error_setg(errp,
>> + "Scalable modern mode: supported values for aw-bits is:
>> %d",
>> + VTD_HOST_AW_48BIT);
>> + return false;
>> + }
>> +
>In both conditions, I would rather test the mode first to make the
>intention clearer.
>For instance,
>
>(s->aw_bits != VTD_HOST_AW_48BIT) && s->scalable_modern
>
>would become
>
>s->scalable_modern && (s->aw_bits != VTD_HOST_AW_48BIT)
Sure, will do.
Thanks
Zhenzhong
>
>Apart from these minor comments, the patch looks good to me
>
>> if (s->scalable_mode && !s->dma_drain) {
>> error_setg(errp, "Need to set dma_drain for scalable mode");
>> return false;
>> --
>> 2.34.1
>>
