From: Tianyu Lan Sent: Monday, September 17, 2018 8:19 PM
>
> #include
> #include
> #include
> #include
> +#include
Hopefully asm/kvm_host.h does not need to be #included, given
the new code structure.
>
> #include
>
> +/*
> + * MAX_FLUSH_PAGES = "additional_pages" + 1. It's limited
> + * by the bitwidth of "additional_pages" in union hv_gpa_page_range.
> + */
> +#define MAX_FLUSH_PAGES (2048)
> +
> +/*
> + * All input flush parameters are in single page. The max flush count
> + * is equal with how many entries of union hv_gpa_page_range can be
> + * populated in the input parameter page. MAX_FLUSH_REP_COUNT
> + * = (4096 - 16) / 8. (“Page Size” - "Address Space" - "Flags") /
> + * "GPA Range".
> + */
> +#define MAX_FLUSH_REP_COUNT (510)
> +
I would recommend putting the above two definitions in
hyperv-tlfs.h. They are directly tied to the data structures defined
by Hyper-V in the TLFS. Put MAX_FLUSH_PAGES immediately after
the definition for hv_gpa_page_range so that the dependency is
obvious.
For MAX_FLUSH_REP_COUNT, can you do the calculation in
the #define rather than just in the comment? Alternatively, define
the gpa_list[] array to be of MAX_FLUSH_REP_COUNT size, and then
add a compile time assert that the size of struct
hv_guest_mapping_flush_list is exactly one page in size. It's just
a good way to use the compiler to help check for mistakes.
Also prefix them both with HV_ since they will be more
globally visible as part of hyperv-tlfs.h.
> int hyperv_flush_guest_mapping(u64 as)
> {
> struct hv_guest_mapping_flush **flush_pcpu;
> @@ -54,3 +71,89 @@ int hyperv_flush_guest_mapping(u64 as)
> return ret;
> }
> EXPORT_SYMBOL_GPL(hyperv_flush_guest_mapping);
> +
> +static int fill_flush_list(union hv_gpa_page_range gpa_list[],
> + int offset, u64 start_gfn, u64 pages)
> +{
> + int gpa_n = offset;
> + u64 cur = start_gfn;
> + u64 additional_pages;
> +
> + do {
> + if (gpa_n >= MAX_FLUSH_REP_COUNT) {
> + pr_warn("Request exceeds HvFlushGuestList max flush
> count.");
> + return -ENOSPC;
I wonder if the warning is really needed. When the error is returned up
through the higher levels of code, won't the higher levels just fallback to
the non-enlightened flush code? So nothing is actually goes wrong; it's just
that a slower code path gets taken. A comment about such expectations
might be helpful.
> + }
> +
> + if (pages > MAX_FLUSH_PAGES) {
> + additional_pages = MAX_FLUSH_PAGES - 1;
> + pages -= MAX_FLUSH_PAGES;
> + } else {
> + additional_pages = pages - 1;
> + pages = 0;
> + }
The above code is really doing:
additional_pages = min(pages, MAX_FLUSH_PAGES) - 1;
pages -= additional_pages + 1;
And you might want to move the decrement of 'pages' down to the
bottom of the loop where you update the other loop variables.
> +
> + gpa_list[gpa_n].page.additional_pages = additional_pages;
> + gpa_list[gpa_n].page.largepage = false;
> + gpa_list[gpa_n].page.basepfn = cur;
> +
> + cur += additional_pages + 1;
> + gpa_n++;
> + } while (pages > 0);
> +
> + return gpa_n;
> +}
> +
> +int hyperv_flush_guest_mapping_range(u64 as, struct hyperv_tlb_range *range)
> +{
> + struct hv_guest_mapping_flush_list **flush_pcpu;
> + struct hv_guest_mapping_flush_list *flush;
> + u64 status = 0;
> + unsigned long flags;
> + int ret = -ENOTSUPP;
> + int gpa_n = 0;
> +
> + if (!hv_hypercall_pg)
> + goto fault;
> +
> + local_irq_save(flags);
> +
> + flush_pcpu = (struct hv_guest_mapping_flush_list **)
> + this_cpu_ptr(hyperv_pcpu_input_arg);
> +
> + flush = *flush_pcpu;
> + if (unlikely(!flush)) {
> + local_irq_restore(flags);
> + goto fault;
> + }
> +
> + flush->address_space = as;
> + flush->flags = 0;
> +
> + if (!range->flush_list)
> + gpa_n = fill_flush_list(flush->gpa_list, gpa_n,
> + range->start_gfn, range->pages);
> + else if (range->parse_flush_list_func)
> + gpa_n = range->parse_flush_list_func(flush->gpa_list, gpa_n,
> + range->flush_list, fill_flush_list);
> + else
> + gpa_n = -1;
> +
> + if (gpa_n < 0) {
> + local_irq_restore(flags);
> + goto fault;
> + }
> +
> + status = hv_do_rep_hypercall(HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST,
> + gpa_n, 0, flush, NULL);
> +
> + local_irq_restore(flags);
> +
> + if (!(status & HV_HYPERCALL_RESULT_MASK))
> + ret = 0;
> + else
> + ret = status;
> +fault:
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(hyperv_flush_guest_mapping_r