Re: [PART1 RFC 9/9] svm: Manage vcpu load/unload when enable AVIC

[Paolo Bonzini]

On 12/02/2016 14:59, Suravee Suthikulpanit wrote:
> +
> +     if (is_running) {
> +             phys_addr_t pa = PFN_PHYS(page_to_pfn(svm->avic_bk_page));
> +
> +             entry->bk_pg_ptr = (pa >> 12) & 0xffffffffff;
> +             entry->valid = 1;
> +             entry->host_phy_apic_id = h_phy_apic_id;
> +             barrier();
> +             entry->is_running = is_running;

I'm not sure if you can rely on the compiler doing the right thing here.
 I would prefer something like:

        new_entry = READ_ONCE(entry);
        new_entry.bk_pg_ptr = (pa >> 12) & 0xffffffffff;
        new_entry.valid = 1;
        new_entry.host_phy_apic_id = h_phy_apic_id;
        new_entry.is_running = is_running;
        WRITE_ONCE(entry, new_entry);

Paolo