linux-kernel - [PATCH v2 1/2] selftests: KVM: align guest physical memory base address to 1GB

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Message-Id: <20210829182641.2505220-2-mizhang@google.com>
Date:   Sun, 29 Aug 2021 18:26:40 +0000
From:   Mingwei Zhang <mizhang@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sean Christopherson <seanjc@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        Peter Xu <peterx@...hat.com>, Ben Gardon <bgardon@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>
Subject: [PATCH v2 1/2] selftests: KVM: align guest physical memory base
 address to 1GB

Existing selftest library function always allocates GPA range that aligns
to the end of GPA address space, ie., the allocated GPA range guarantees to
end at the last available GPA. This ends up with the fact that selftest
programs cannot control the alignment of the base GPA. Depending on the
size of the allocation, the base GPA may align only on a 4K based
bounday.

The alignment of base GPA sometimes creates problems for dirty logging
selftest where a 2MB-aligned or 1GB-aligned base GPA is needed to
create NPT/EPT mappings for hugepages.

So, fix this issue and ensure all GPA allocation starts from a 1GB bounary
in all architectures.

Cc: Sean Christopherson <seanjc@...gle.com>
Cc: David Matlack <dmatlack@...gle.com>
Cc: Jing Zhang <jingzhangos@...gle.com>
Cc: Peter Xu <peterx@...hat.com>

Suggested-by: Ben Gardon <bgardon@...gle.com>
Signed-off-by: Mingwei Zhang <mizhang@...gle.com>
---
 tools/testing/selftests/kvm/lib/perf_test_util.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index 0ef80dbdc116..96c30b8d6593 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -93,10 +93,10 @@ 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);
-#ifdef __s390x__
-	/* Align to 1M (segment size) */
-	guest_test_phys_mem &= ~((1 << 20) - 1);
-#endif
+
+	/* Align to 1G for all architectures */
+	guest_test_phys_mem &= ~((1 << 30) - 1);
+
 	pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
 
 	/* Add extra memory slots for testing */
-- 
2.33.0.259.gc128427fd7-goog