Re: [RFC PATCH 02/20] intel_iommu: exposed extended-context mode to guest

Lan Tianyu
2017-04-28T06:09:00Z

On 2017年04月27日 18:32, Peter Xu wrote:
> On Wed, Apr 26, 2017 at 06:06:32PM +0800, Liu, Yi L wrote:
>> VT-d implementations reporting PASID or PRS fields as "Set", must also
>> report ecap.ECS as "Set". Extended-Context is required for SVM.
>>
>> When ECS is reported, intel iommu driver would initiate extended root entry
>> and extended context entry, and also PASID table if there is any SVM capable
>> device.
>>
>> Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
>> ---
>> hw/i386/intel_iommu.c | 131 +++++++++++++++++++++++++++--------------
>> hw/i386/intel_iommu_internal.h | 9 +++
>> include/hw/i386/intel_iommu.h | 2 +-
>> 3 files changed, 97 insertions(+), 45 deletions(-)
>>
>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
>> index 400d0d1..bf98fa5 100644
>> --- a/hw/i386/intel_iommu.c
>> +++ b/hw/i386/intel_iommu.c
>> @@ -497,6 +497,11 @@ static inline bool vtd_root_entry_present(VTDRootEntry *root)
>> return root->val & VTD_ROOT_ENTRY_P;
>> }
>>
>> +static inline bool vtd_root_entry_upper_present(VTDRootEntry *root)
>> +{
>> + return root->rsvd & VTD_ROOT_ENTRY_P;
>> +}
>> +
>> static int vtd_get_root_entry(IntelIOMMUState *s, uint8_t index,
>> VTDRootEntry *re)
>> {
>> @@ -509,6 +514,9 @@ static int vtd_get_root_entry(IntelIOMMUState *s, uint8_t index,
>> return -VTD_FR_ROOT_TABLE_INV;
>> }
>> re->val = le64_to_cpu(re->val);
>> + if (s->ecs) {
>> + re->rsvd = le64_to_cpu(re->rsvd);
>> + }
>
> I feel it slightly hacky to play with re->rsvd. How about:
>
> union VTDRootEntry {
> struct {
> uint64_t val;
> uint64_t rsvd;
> } base;
> struct {
> uint64_t ext_lo;
> uint64_t ext_hi;
> } extended;
> };
>
> (Or any better way that can get rid of rsvd...)
>
> Even:
>
> struct VTDRootEntry {
> union {
> struct {
> uint64_t val;
> uint64_t rsvd;
> } base;
> struct {
> uint64_t ext_lo;
> uint64_t ext_hi;
> } extended;
> } data;
> bool extended;
> };
>
> Then we read the entry into data, and setup extended bit. A benefit of
> it is that we may avoid passing around IntelIOMMUState everywhere to
> know whether we are using extended context entries.
>
>> return 0;
>> }
>>
>> @@ -517,19 +525,30 @@ static inline bool vtd_context_entry_present(VTDContextEntry *context)
>> return context->lo & VTD_CONTEXT_ENTRY_P;
>> }
>>
>> -static int vtd_get_context_entry_from_root(VTDRootEntry *root, uint8_t index,
>> - VTDContextEntry *ce)
>> +static int vtd_get_context_entry_from_root(IntelIOMMUState *s,
>> + VTDRootEntry *root, uint8_t index, VTDContextEntry *ce)
>> {
>> - dma_addr_t addr;
>> + dma_addr_t addr, ce_size;
>>
>> /* we have checked that root entry is present */
>> - addr = (root->val & VTD_ROOT_ENTRY_CTP) + index * sizeof(*ce);
>> - if (dma_memory_read(&address_space_memory, addr, ce, sizeof(*ce))) {
>> + ce_size = (s->ecs) ? (2 * sizeof(*ce)) : (sizeof(*ce));
>> + addr = (s->ecs && (index > 0x7f)) ?
>> + ((root->rsvd & VTD_ROOT_ENTRY_CTP) + (index - 0x80) * ce_size) :
>> + ((root->val & VTD_ROOT_ENTRY_CTP) + index * ce_size);
>> +
>> + if (dma_memory_read(&address_space_memory, addr, ce, ce_size)) {
>> trace_vtd_re_invalid(root->rsvd, root->val);
>> return -VTD_FR_CONTEXT_TABLE_INV;
>> }
>> - ce->lo = le64_to_cpu(ce->lo);
>> - ce->hi = le64_to_cpu(ce->hi);
>> +
>> + ce[0].lo = le64_to_cpu(ce[0].lo);
>> + ce[0].hi = le64_to_cpu(ce[0].hi);
>
> Again, I feel this even hackier. :)
>
> I would slightly prefer to play the same union trick to context
> entries, just like what I proposed to the root entries above...
>
>> +
>> + if (s->ecs) {
>> + ce[1].lo = le64_to_cpu(ce[1].lo);
>> + ce[1].hi = le64_to_cpu(ce[1].hi);
>> + }
>> +
>> return 0;
>> }
>>
>> @@ -595,9 +614,11 @@ static inline uint32_t vtd_get_agaw_from_context_entry(VTDContextEntry *ce)
>> return 30 + (ce->hi & VTD_CONTEXT_ENTRY_AW) * 9;
>> }
>>
>> -static inline uint32_t vtd_ce_get_type(VTDContextEntry *ce)
>> +static inline uint32_t vtd_ce_get_type(IntelIOMMUState *s,
>> + VTDContextEntry *ce)
>> {
>> - return ce->lo & VTD_CONTEXT_ENTRY_TT;
>> + return s->ecs ? (ce->lo & VTD_CONTEXT_ENTRY_TT) :
>> + (ce->lo & VTD_EXT_CONTEXT_ENTRY_TT);
>> }
>>
>> static inline uint64_t vtd_iova_limit(VTDContextEntry *ce)
>> @@ -842,16 +863,20 @@ static int vtd_dev_to_context_entry(IntelIOMMUState *s, uint8_t bus_num,
>> return ret_fr;
>> }
>>
>> - if (!vtd_root_entry_present(&re)) {
>> + if (!vtd_root_entry_present(&re) ||
>> + (s->ecs && (devfn > 0x7f) && (!vtd_root_entry_upper_present(&re)))) {
>> /* Not error - it's okay we don't have root entry. */
>> trace_vtd_re_not_present(bus_num);
>> return -VTD_FR_ROOT_ENTRY_P;
>> - } else if (re.rsvd || (re.val & VTD_ROOT_ENTRY_RSVD)) {
>> - trace_vtd_re_invalid(re.rsvd, re.val);
>> - return -VTD_FR_ROOT_ENTRY_RSVD;
>> + }
>> + if ((s->ecs && (devfn > 0x7f) && (re.rsvd & VTD_ROOT_ENTRY_RSVD)) ||
>> + (s->ecs && (devfn < 0x80) && (re.val & VTD_ROOT_ENTRY_RSVD)) ||
>> + ((!s->ecs) && (re.rsvd || (re.val & VTD_ROOT_ENTRY_RSVD)))) {
>> + trace_vtd_re_invalid(re.rsvd, re.val);
>> + return -VTD_FR_ROOT_ENTRY_RSVD;
>
> Nit: I feel like we can better wrap these 0x7f and 0x80 into helper
> functions, especially if with above structure change...
>
> (will hold here...)
>
> Thanks,
>

It's possible to add helper macro to check bits in context entry and
extend context entry and put the check of ecs mode into helper macro?

--
Best regards
Tianyu Lan