Re: [PATCH v5 08/20] intel_iommu: Check stage-1 translation result with interrupt range

[CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>]

On 13/11/2024 09:49, Duan, Zhenzhong wrote:
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>> -----Original Message-----
>> From: CLEMENT MATHIEU--DRIF <clement.mathieu--drif@eviden.com>
>> Sent: Wednesday, November 13, 2024 2:56 PM
>> Subject: Re: [PATCH v5 08/20] intel_iommu: Check stage-1 translation result with
>> interrupt range
>>
>>
>> On 11/11/2024 09:34, Zhenzhong Duan wrote:
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>> email comes from a known sender and you know the content is safe.
>>>
>>> Per VT-d spec 4.1 section 3.15, "Untranslated requests and translation
>>> requests that result in an address in the interrupt range will be
>>> blocked with condition code LGN.4 or SGN.8."
>>>
>>> This applies to both stage-1 and stage-2 IOMMU page table, move the
>>> check from vtd_iova_to_slpte() to vtd_do_iommu_translate() so stage-1
>>> page table could also be checked.
>>>
>>> By this chance, update the comment with correct section number.
>>>
>>> Suggested-by: Yi Liu <yi.l.liu@intel.com>
>>> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
>>> ---
>>>    hw/i386/intel_iommu.c | 48 ++++++++++++++++++++++---------------------
>>>    1 file changed, 25 insertions(+), 23 deletions(-)
>>>
>>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>>> index 4cc4d668fc..e651401db1 100644
>>> --- a/hw/i386/intel_iommu.c
>>> +++ b/hw/i386/intel_iommu.c
>>> @@ -1138,7 +1138,6 @@ static int vtd_iova_to_slpte(IntelIOMMUState *s,
>> VTDContextEntry *ce,
>>>        uint32_t offset;
>>>        uint64_t slpte;
>>>        uint64_t access_right_check;
>>> -    uint64_t xlat, size;
>>>
>>>        if (!vtd_iova_sl_range_check(s, iova, ce, aw_bits, pasid)) {
>>>            error_report_once("%s: detected IOVA overflow (iova=0x%" PRIx64 ","
>>> @@ -1191,28 +1190,7 @@ static int vtd_iova_to_slpte(IntelIOMMUState *s,
>> VTDContextEntry *ce,
>>>            level--;
>>>        }
>>>
>>> -    xlat = vtd_get_pte_addr(*slptep, aw_bits);
>>> -    size = ~vtd_pt_level_page_mask(level) + 1;
>>> -
>>> -    /*
>>> -     * From VT-d spec 3.14: Untranslated requests and translation
>>> -     * requests that result in an address in the interrupt range will be
>>> -     * blocked with condition code LGN.4 or SGN.8.
>>> -     */
>>> -    if ((xlat > VTD_INTERRUPT_ADDR_LAST ||
>>> -         xlat + size - 1 < VTD_INTERRUPT_ADDR_FIRST)) {
>>> -        return 0;
>>> -    } else {
>>> -        error_report_once("%s: xlat address is in interrupt range "
>>> -                          "(iova=0x%" PRIx64 ", level=0x%" PRIx32 ", "
>>> -                          "slpte=0x%" PRIx64 ", write=%d, "
>>> -                          "xlat=0x%" PRIx64 ", size=0x%" PRIx64 ", "
>>> -                          "pasid=0x%" PRIx32 ")",
>>> -                          __func__, iova, level, slpte, is_write,
>>> -                          xlat, size, pasid);
>>> -        return s->scalable_mode ? -VTD_FR_SM_INTERRUPT_ADDR :
>>> -                                  -VTD_FR_INTERRUPT_ADDR;
>>> -    }
>>> +    return 0;
>>>    }
>>>
>>>    typedef int (*vtd_page_walk_hook)(const IOMMUTLBEvent *event, void
>> *private);
>>> @@ -2064,6 +2042,7 @@ static bool
>> vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus,
>>>        uint8_t access_flags;
>>>        bool rid2pasid = (pasid == PCI_NO_PASID) && s->root_scalable;
>>>        VTDIOTLBEntry *iotlb_entry;
>>> +    uint64_t xlat, size;
>>>
>>>        /*
>>>         * We have standalone memory region for interrupt addresses, we
>>> @@ -2173,6 +2152,29 @@ static bool
>> vtd_do_iommu_translate(VTDAddressSpace *vtd_as, PCIBus *bus,
>>>            ret_fr = vtd_iova_to_slpte(s, &ce, addr, is_write, &pte, &level,
>>>                                       &reads, &writes, s->aw_bits, pasid);
>>>        }
>>> +    if (!ret_fr) {
>>> +        xlat = vtd_get_pte_addr(pte, s->aw_bits);
>>> +        size = ~vtd_pt_level_page_mask(level) + 1;
>>> +
>>> +        /*
>>> +         * Per VT-d spec 4.1 section 3.15: Untranslated requests and translation
>>> +         * requests that result in an address in the interrupt range will be
>>> +         * blocked with condition code LGN.4 or SGN.8.
>>> +         */
>>> +        if ((xlat <= VTD_INTERRUPT_ADDR_LAST &&
>>> +             xlat + size - 1 >= VTD_INTERRUPT_ADDR_FIRST)) {
>>> +            error_report_once("%s: xlat address is in interrupt range "
>>> +                              "(iova=0x%" PRIx64 ", level=0x%" PRIx32 ", "
>>> +                              "pte=0x%" PRIx64 ", write=%d, "
>>> +                              "xlat=0x%" PRIx64 ", size=0x%" PRIx64 ", "
>>> +                              "pasid=0x%" PRIx32 ")",
>>> +                              __func__, addr, level, pte, is_write,
>>> +                              xlat, size, pasid);
>> Hi Zhenzhong,
>>
>> Shouldn't we add the pgtt value to this trace as it can now be generated
>> by both FL and SL?
> Hi Clement,
>
> We don't always have a pgtt value to dump, e.g., when vIOMMU is in legacy mode.
> Meanwhile we have other way to get pgtt if there is, e.g., from qemu cmdline.
> Pgtt is also unrelated to the error itself, so I'd like to skip pgtt dump to be a bit simple.

Hi,
pgtt is initialized just above and is set to SLT when the vIOMMU is in 
legacy mode.
But it's fine, we can keep the patch as is!
Thanks

Reviewed-by: Clément Mathieu--Drif<clement.mathieu--drif@eviden.com>



>
> Thanks
> Zhenzhong
>