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

Liu, Yi L
2017-04-28T09:56:25Z

On Fri, Apr 28, 2017 at 02:00:15PM +0800, Lan Tianyu wrote:
> 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?

yes, would add accordingly in next version.

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