Re: [PATCH 7/9] KVM: selftests: Add parameter to _vm_create for memslot 0 base paddr

Andrew Jones
2019-10-03T08:10:17Z

On Fri, Sep 27, 2019 at 09:18:35AM -0700, Ben Gardon wrote:
> KVM creates internal memslots between 3 and 4 GiB paddrs on the first
> vCPU creation. If memslot 0 is large enough it collides with these
> memslots an causes vCPU creation to fail. Add a paddr parameter for
> memslot 0 so that tests which support large VMs can relocate memslot 0
> above 4 GiB.
>
> Signed-off-by: Ben Gardon <bgardon@google.com>
> ---
> tools/testing/selftests/kvm/demand_paging_test.c | 2 +-
> tools/testing/selftests/kvm/dirty_log_test.c | 2 +-
> tools/testing/selftests/kvm/include/kvm_util.h | 3 ++-
> tools/testing/selftests/kvm/lib/kvm_util.c | 7 ++++---
> 4 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index fe6c5a4f8b8c2..eb1f7e4b83de3 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -171,7 +171,7 @@ static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
> pages += (2 * pages) / PTES_PER_PT;
> pages += ((2 * vcpus * vcpu_wss) >> PAGE_SHIFT_4K) / PTES_PER_PT;
>
> - vm = _vm_create(mode, pages, O_RDWR);
> + vm = vm_create(mode, pages, O_RDWR);

Eh, we should have removed/renamed _vm_create() with 12c386b23083 ("KVM:
selftests: Move vm type into _vm_create() internally")

> kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
> #ifdef __x86_64__
> vm_create_irqchip(vm);
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index 5614222a66285..181eac3a12b66 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -252,7 +252,7 @@ static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,
> struct kvm_vm *vm;
> uint64_t extra_pg_pages = extra_mem_pages / 512 * 2;
>
> - vm = _vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_pages, O_RDWR);
> + vm = vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_pages, O_RDWR);
> kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
> #ifdef __x86_64__
> vm_create_irqchip(vm);
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 29cccaf96baf6..4f672c00c9e9b 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -69,7 +69,8 @@ int kvm_check_cap(long cap);
> int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap);
>
> struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
> -struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
> +struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t guest_paddr,
> + uint64_t phy_pages, int perm);

But now we need it again. Or do we? How about just documenting that if
phy_pages is >= some-limit then the base address will be 4G, otherwise
it will be zero? The documentation (comment above _vm_create()) needs to
be updated with this patch regardless. Either the behavior changes or a
new parameter is added.

If you go with my suggestion to just use 4G when phy_pages are large, then
please rename _vm_create to vm_create.

Thanks,
drew

> void kvm_vm_free(struct kvm_vm *vmp);
> void kvm_vm_restart(struct kvm_vm *vmp, int perm);
> void kvm_vm_release(struct kvm_vm *vmp);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 80a338b5403c3..7ec2bbdaba875 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -132,7 +132,8 @@ _Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
> * descriptor to control the created VM is created with the permissions
> * given by perm (e.g. O_RDWR).
> */
> -struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
> +struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t guest_paddr,
> + uint64_t phy_pages, int perm)
> {
> struct kvm_vm *vm;
>
> @@ -229,14 +230,14 @@ struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
> vm->vpages_mapped = sparsebit_alloc();
> if (phy_pages != 0)
> vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> - 0, 0, phy_pages, 0);
> + guest_paddr, 0, phy_pages, 0);
>
> return vm;
> }
>
> struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
> {
> - return _vm_create(mode, phy_pages, perm);
> + return _vm_create(mode, 0, phy_pages, perm);
> }
>
> /*
> --
> 2.23.0.444.g18eeb5a265-goog
>