[PATCH] KVM: selftests: Stop assuming stats are contiguous in kvm_binary_stats_test

[PATCH] KVM: selftests: Stop assuming stats are contiguous in kvm_binary_stats_test

[David Matlack]

From: Jing Zhang <jingzhangos@google.com>

Remove the assumption from kvm_binary_stats_test that all stats are
laid out contiguously in memory. The current stats in KVM are
contiguously laid out in memory, but that may change in the future and
the ABI specifically allows holes in the stats data (since each stat
exposes its own offset).

While here drop the check that each stats' offset is less than
size_data, as that is now always true by construction.

Link: https://lore.kernel.org/kvm/20221208193857.4090582-9-dmatlack@google.com/
Fixes: 0b45d58738cd ("KVM: selftests: Add selftest for KVM statistics data binary interface")
Signed-off-by: Jing Zhang <jingzhangos@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
[Re-worded the commit message.]

Signed-off-by: David Matlack <dmatlack@google.com>
---
 tools/testing/selftests/kvm/kvm_binary_stats_test.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
index 894417c96f70..a7001e29dc06 100644
--- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c
+++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
@@ -134,7 +134,7 @@ static void stats_test(int stats_fd)
 				    "Bucket size of stats (%s) is not zero",
 				    pdesc->name);
 		}
-		size_data += pdesc->size * sizeof(*stats_data);
+		size_data = max(size_data, pdesc->offset + pdesc->size * sizeof(*stats_data));
 	}
 
 	/*
@@ -149,14 +149,6 @@ static void stats_test(int stats_fd)
 	TEST_ASSERT(size_data >= header.num_desc * sizeof(*stats_data),
 		    "Data size is not correct");
 
-	/* Check stats offset */
-	for (i = 0; i < header.num_desc; ++i) {
-		pdesc = get_stats_descriptor(stats_desc, i, &header);
-		TEST_ASSERT(pdesc->offset < size_data,
-			    "Invalid offset (%u) for stats: %s",
-			    pdesc->offset, pdesc->name);
-	}
-
 	/* Allocate memory for stats data */
 	stats_data = malloc(size_data);
 	TEST_ASSERT(stats_data, "Allocate memory for stats data");

base-commit: de60733246ff4545a0483140c1f21426b8d7cb7f
prerequisite-patch-id: 42a76ce7cec240776c21f674e99e893a3a6bee58
-- 
2.39.0.246.g2a6d74b583-goog

Re: [PATCH] KVM: selftests: Stop assuming stats are contiguous in kvm_binary_stats_test

[Sean Christopherson]

On Tue, 17 Jan 2023 14:27:07 -0800, David Matlack wrote:
> Remove the assumption from kvm_binary_stats_test that all stats are
> laid out contiguously in memory. The current stats in KVM are
> contiguously laid out in memory, but that may change in the future and
> the ABI specifically allows holes in the stats data (since each stat
> exposes its own offset).
> 
> While here drop the check that each stats' offset is less than
> size_data, as that is now always true by construction.
> 
> [...]

Applied to kvm-x86 selftests, thanks!

[1/1] KVM: selftests: Stop assuming stats are contiguous in kvm_binary_stats_test
      https://github.com/kvm-x86/linux/commit/d9e552858fab

--
https://github.com/kvm-x86/linux/tree/next
https://github.com/kvm-x86/linux/tree/fixes