Re: [PATCH v4 07/10] KVM: selftests: Support multiple vCPUs in demand paging test

On Thu, Jan 23, 2020 at 10:04:33AM -0800, Ben Gardon wrote: ...

-static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,

• 		uint64_t extra_mem_pages, void *guest_code)
  

+#define PAGE_SHIFT_4K 12 +#define PTES_PER_4K_PT 512

+static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,

• 		uint64_t vcpu_memory_bytes)
  

{ struct kvm_vm *vm;

• uint64_t extra_pg_pages = extra_mem_pages / 512 * 2;

• uint64_t pages = DEFAULT_GUEST_PHY_PAGES;
• /* Account for a few pages per-vCPU for stacks */
• pages += DEFAULT_STACK_PGS * vcpus;
• /*

• * Reserve twice the ammount of memory needed to map the test region and
  

• * the page table / stacks region, at 4k, for page tables. Do the
  

• * calculation with 4K page size: the smallest of all archs. (e.g., 64K
  

• * page size guest will need even less memory for page tables).
  

• */
  

• pages += (2 * pages) / PTES_PER_4K_PT;
• pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /

•  PTES_PER_4K_PT;
  

pages needs to be rounded up to the next multiple of 16 in order for this to work on aarch64 machines with 64k pages.

Thanks, drew