[PATCH v2 8/8] KVM: selftests: Move large memslots above KVM internal memslots in _vm_create

Ben Gardon
2019-12-16T21:36:15Z

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. When requesting more than 3G,
start memslot 0 at 4G in _vm_create.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
tools/testing/selftests/kvm/lib/kvm_util.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 41cf45416060f..886d58e6cac39 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -113,6 +113,8 @@ const char * const vm_guest_mode_string[] = {
_Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
"Missing new mode strings?");

+#define KVM_INTERNAL_MEMSLOTS_START_PADDR (3UL << 30)
+#define KVM_INTERNAL_MEMSLOTS_END_PADDR (4UL << 30)
/*
* VM Create
*
@@ -128,13 +130,16 @@ _Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
*
* Creates a VM with the mode specified by mode (e.g. VM_MODE_P52V48_4K).
* When phy_pages is non-zero, a memory region of phy_pages physical pages
- * is created and mapped starting at guest physical address 0. The file
- * descriptor to control the created VM is created with the permissions
- * given by perm (e.g. O_RDWR).
+ * is created. If phy_pages is less that 3G, it is mapped starting at guest
+ * physical address 0. If phy_pages is greater than 3G it is mapped starting
+ * 4G into the guest physical address space to avoid KVM internal memslots
+ * which map the region between 3G and 4G. The file 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;
+ uint64_t guest_paddr = 0;

DEBUG("Testing guest mode: %s\n", vm_guest_mode_string(mode));

@@ -227,9 +232,11 @@ struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)

/* Allocate and setup memory for guest. */
vm->vpages_mapped = sparsebit_alloc();
+ if (guest_paddr + phy_pages > KVM_INTERNAL_MEMSLOTS_START_PADDR)
+ guest_paddr = KVM_INTERNAL_MEMSLOTS_END_PADDR;
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;
}
--
2.24.1.735.g03f4e72817-goog