linux-kernel - [PATCH 05/15] KVM: selftests: Require GPA to be aligned when backed by hugepages

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Message-Id: <20210210230625.550939-6-seanjc@google.com>
Date:   Wed, 10 Feb 2021 15:06:15 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>,
        Ben Gardon <bgardon@...gle.com>,
        Yanan Wang <wangyanan55@...wei.com>,
        Andrew Jones <drjones@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Aaron Lewis <aaronlewis@...gle.com>
Subject: [PATCH 05/15] KVM: selftests: Require GPA to be aligned when backed
 by hugepages

Assert that the GPA for a memslot backed by a hugepage is 1gb aligned,
and fix perf_test_util accordingly.  Lack of GPA alignment prevents KVM
from backing the guest with hugepages, e.g. x86's write-protection of
hugepages when dirty logging is activated is otherwise not exercised.

Add a comment explaining that guest_page_size is for non-huge pages to
try and avoid confusion about what it actually tracks.

Cc: Ben Gardon <bgardon@...gle.com>
Cc: Yanan Wang <wangyanan55@...wei.com>
Cc: Andrew Jones <drjones@...hat.com>
Cc: Peter Xu <peterx@...hat.com>
Cc: Aaron Lewis <aaronlewis@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/lib/kvm_util.c       | 2 ++
 tools/testing/selftests/kvm/lib/perf_test_util.c | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 2e497fbab6ae..855d20784ba7 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -735,6 +735,8 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 	else
 		ASSERT_EQ(src_type, VM_MEM_SRC_ANONYMOUS);
 
+	ASSERT_EQ(guest_paddr, align(guest_paddr, alignment));
+
 	/* Add enough memory to align up if necessary */
 	if (alignment > 1)
 		region->mmap_size += alignment;
diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index 81490b9b4e32..f187b86f2e14 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -58,6 +58,11 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
 	pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
 
 	perf_test_args.host_page_size = getpagesize();
+
+	/*
+	 * Snapshot the non-huge page size.  This is used by the guest code to
+	 * access/dirty pages at the logging granularity.
+	 */
 	perf_test_args.guest_page_size = vm_guest_mode_params[mode].page_size;
 
 	guest_num_pages = vm_adjust_num_guest_pages(mode,
@@ -87,6 +92,10 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
 	guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
 			      perf_test_args.guest_page_size;
 	guest_test_phys_mem &= ~(perf_test_args.host_page_size - 1);
+	if (backing_src == VM_MEM_SRC_ANONYMOUS_THP ||
+	    backing_src == VM_MEM_SRC_ANONYMOUS_HUGETLB)
+		guest_test_phys_mem &= ~(KVM_UTIL_HUGEPAGE_ALIGNMENT - 1);
+
 #ifdef __s390x__
 	/* Align to 1M (segment size) */
 	guest_test_phys_mem &= ~((1 << 20) - 1);
-- 
2.30.0.478.g8a0d178c01-goog