linux-kernel - [PATCH v4 10/10] KVM: selftests: Move memslot 0 above KVM internal memslots

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Date:   Thu, 23 Jan 2020 10:04:36 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>,
        Andrew Jones <drjones@...hat.com>,
        Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v4 10/10] KVM: selftests: Move memslot 0 above KVM internal memslots

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. Instead of creating memslot 0
at paddr 0, start it 4G into the guest physical address space.

Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 5b971c04f1643..427c88d32e988 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -130,9 +130,11 @@ _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, starting at 4G into the guest physical address space to avoid
+ * KVM internal memslots which map the region between 3G and 4G. If tests need
+ * to use the physical region between 0 and 3G, they can allocate another
+ * memslot for that region. 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)
 {
@@ -231,7 +233,8 @@ 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);
+					    KVM_INTERNAL_MEMSLOTS_END_PADDR,
+					    0, phy_pages, 0);
 
 	return vm;
 }
-- 
2.25.0.341.g760bfbb309-goog