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Date:   Tue,  3 May 2022 18:30:43 +0000
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Subject: [PATCH v7 09/11] KVM: selftests: Factor out calculation of pages
 needed for a VM
From:   Ben Gardon <bgardon@google.com>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        David Matlack <dmatlack@google.com>,
        Jim Mattson <jmattson@google.com>,
        David Dunn <daviddunn@google.com>,
        Jing Zhang <jingzhangos@google.com>,
        Junaid Shahid <junaids@google.com>,
        Ben Gardon <bgardon@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Factor out the calculation of the number of pages needed for a VM to
make it easier to separate creating the VM and adding vCPUs.

Reviewed-by: David Matlack <dmatlack@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
---
 .../selftests/kvm/include/kvm_util_base.h     |  4 ++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 59 ++++++++++++++-----
 2 files changed, 47 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 001b55ae25f8..1dac3c6607f1 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -312,6 +312,10 @@ vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
 			      vm_paddr_t paddr_min, uint32_t memslot);
 vm_paddr_t vm_alloc_page_table(struct kvm_vm *vm);
 
+uint64_t vm_pages_needed(enum vm_guest_mode mode, uint32_t nr_vcpus,
+			 uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
+			 uint32_t num_percpu_pages);
+
 /*
  * Create a VM with reasonable defaults
  *
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 6930ba298170..27ffd2537df6 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -377,7 +377,7 @@ struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages)
 }
 
 /*
- * VM Create with customized parameters
+ * Get the number of pages needed for a VM
  *
  * Input Args:
  *   mode - VM Mode (e.g. VM_MODE_P52V48_4K)
@@ -385,27 +385,17 @@ struct kvm_vm *vm_create_without_vcpus(enum vm_guest_mode mode, uint64_t pages)
  *   slot0_mem_pages - Slot0 physical memory size
  *   extra_mem_pages - Non-slot0 physical memory total size
  *   num_percpu_pages - Per-cpu physical memory pages
- *   guest_code - Guest entry point
- *   vcpuids - VCPU IDs
  *
  * Output Args: None
  *
  * Return:
- *   Pointer to opaque structure that describes the created VM.
- *
- * Creates a VM with the mode specified by mode (e.g. VM_MODE_P52V48_4K),
- * with customized slot0 memory size, at least 512 pages currently.
- * extra_mem_pages is only used to calculate the maximum page table size,
- * no real memory allocation for non-slot0 memory in this function.
+ *   The number of pages needed for the VM.
  */
-struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
-				    uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
-				    uint32_t num_percpu_pages, void *guest_code,
-				    uint32_t vcpuids[])
+uint64_t vm_pages_needed(enum vm_guest_mode mode, uint32_t nr_vcpus,
+			 uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
+			 uint32_t num_percpu_pages)
 {
 	uint64_t vcpu_pages, extra_pg_pages, pages;
-	struct kvm_vm *vm;
-	int i;
 
 	/* Force slot0 memory size not small than DEFAULT_GUEST_PHY_PAGES */
 	if (slot0_mem_pages < DEFAULT_GUEST_PHY_PAGES)
@@ -421,11 +411,48 @@ struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
 	extra_pg_pages = (slot0_mem_pages + extra_mem_pages + vcpu_pages) / PTES_PER_MIN_PAGE * 2;
 	pages = slot0_mem_pages + vcpu_pages + extra_pg_pages;
 
+	pages = vm_adjust_num_guest_pages(mode, pages);
+
+	return pages;
+}
+
+/*
+ * VM Create with customized parameters
+ *
+ * Input Args:
+ *   mode - VM Mode (e.g. VM_MODE_P52V48_4K)
+ *   nr_vcpus - VCPU count
+ *   slot0_mem_pages - Slot0 physical memory size
+ *   extra_mem_pages - Non-slot0 physical memory total size
+ *   num_percpu_pages - Per-cpu physical memory pages
+ *   guest_code - Guest entry point
+ *   vcpuids - VCPU IDs
+ *
+ * Output Args: None
+ *
+ * Return:
+ *   Pointer to opaque structure that describes the created VM.
+ *
+ * Creates a VM with the mode specified by mode (e.g. VM_MODE_P52V48_4K),
+ * with customized slot0 memory size, at least 512 pages currently.
+ * extra_mem_pages is only used to calculate the maximum page table size,
+ * no real memory allocation for non-slot0 memory in this function.
+ */
+struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
+				    uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
+				    uint32_t num_percpu_pages, void *guest_code,
+				    uint32_t vcpuids[])
+{
+	uint64_t pages;
+	struct kvm_vm *vm;
+	int i;
+
 	TEST_ASSERT(nr_vcpus <= kvm_check_cap(KVM_CAP_MAX_VCPUS),
 		    "nr_vcpus = %d too large for host, max-vcpus = %d",
 		    nr_vcpus, kvm_check_cap(KVM_CAP_MAX_VCPUS));
 
-	pages = vm_adjust_num_guest_pages(mode, pages);
+	pages = vm_pages_needed(mode, nr_vcpus, slot0_mem_pages,
+				extra_mem_pages, num_percpu_pages);
 
 	vm = vm_create_without_vcpus(mode, pages);
 
-- 
2.36.0.464.gb9c8b46e94-goog