linux-kernel - [PATCH v2 8/8] KVM: selftests: Move large memslots above KVM internal memslots in _vm

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Message-Id: <20191216213532.91237-10-bgardon@google.com>
Date:   Mon, 16 Dec 2019 13:35:32 -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>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v2 8/8] KVM: selftests: Move large memslots above KVM internal
 memslots in _vm_create

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@...gle.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