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SubjectRe: [PATCHv2 4/6] Crashdump-Accepting-Active-IOMMU-Copy-Translations
On 12/20/13 at 02:04pm, Baoquan He wrote:
> On 12/19/13 at 07:49pm, Bill Sumner wrote:
>
> > +static int copy_page_addr(u64 page_addr, u32 shift, u32 bus, u32 devfn,
> > + u64 pte, struct dmar_domain *domain,
> > + void *parms)
> > +{
> > + struct copy_page_addr_parms *ppap = parms;
> > +
> > + u64 page_size = ((u64)1 << shift); /* page_size */
> > + u64 pfn_lo; /* For reserving IOVA range */
> > + u64 pfn_hi; /* For reserving IOVA range */
> > + struct iova *iova_p; /* For reserving IOVA range */
> > +
> > + if (!ppap) {
> > + pr_err("ERROR: ppap is NULL: 0x%3.3x(%3.3d) DevFn: 0x%3.3x(%3.3d) Page: 0x%16.16llx Size: 0x%16.16llx(%lld)\n",
> > + bus, bus, devfn, devfn, page_addr,
> > + page_size, page_size);
> > + return 0;
> > + }
> > +
>
> > + /* Prepare for a new page */
> > + ppap->first = 0; /* Not first-time anymore */
> > + ppap->bus = bus;
> > + ppap->devfn = devfn;
> > + ppap->shift = shift;
> > + ppap->pte = pte;
> > + ppap->next_addr = page_addr + page_size; /* Next-expected page_addr */
> > +
> > + ppap->page_addr = page_addr; /* Addr(new page) */
> > + ppap->page_size = page_size; /* Size(new page) */
> > +
> > + ppap->domain = domain; /* adr(domain for the new range) */
>
> Here I am confused, ppap is used to collect the copied ranges and
> necessary information. To my understanding, this domain is the
> dmar_domain which the 1st device is on. When ppat->last is set to 1,
> among the whole collected range, there may be many domains. I just feel
> not good for this. Is it OK to define a specific lock for ppap
> structure, possibly? Please correct me if I am wrong.

Well, check it again. It's not about the lock. Just all address is
recorded in one dmar_domain.


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