linux-kernel - [PATCH v4 12/16] KVM: selftests: Add a read-only mprotect() phase to mmu_stress

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Message-ID: <20241128005547.4077116-13-seanjc@google.com>
Date: Wed, 27 Nov 2024 16:55:43 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Paolo Bonzini <pbonzini@...hat.com>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, 
	Sean Christopherson <seanjc@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Andrew Jones <ajones@...tanamicro.com>, James Houghton <jthoughton@...gle.com>, 
	Muhammad Usama Anjum <usama.anjum@...labora.com>
Subject: [PATCH v4 12/16] KVM: selftests: Add a read-only mprotect() phase to mmu_stress_test

Add a third phase of mmu_stress_test to verify that mprotect()ing guest
memory to make it read-only doesn't cause explosions, e.g. to verify KVM
correctly handles the resulting mmu_notifier invalidations.

Reviewed-by: James Houghton <jthoughton@...gle.com>
Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/mmu_stress_test.c | 22 +++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/mmu_stress_test.c b/tools/testing/selftests/kvm/mmu_stress_test.c
index c6bf18cb7c89..0918fade9267 100644
--- a/tools/testing/selftests/kvm/mmu_stress_test.c
+++ b/tools/testing/selftests/kvm/mmu_stress_test.c
@@ -28,6 +28,10 @@ static void guest_code(uint64_t start_gpa, uint64_t end_gpa, uint64_t stride)
 		GUEST_SYNC(i);
 	}
 
+	for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
+		*((volatile uint64_t *)gpa);
+	GUEST_SYNC(2);
+
 	GUEST_ASSERT(0);
 }
 
@@ -95,6 +99,10 @@ static void *vcpu_worker(void *data)
 	run_vcpu(vcpu, 1);
 	rendezvous_with_boss();
 
+	/* Stage 2, read all of guest memory, which is now read-only. */
+	run_vcpu(vcpu, 2);
+	rendezvous_with_boss();
+
 	return NULL;
 }
 
@@ -175,7 +183,7 @@ int main(int argc, char *argv[])
 	const uint64_t start_gpa = SZ_4G;
 	const int first_slot = 1;
 
-	struct timespec time_start, time_run1, time_reset, time_run2;
+	struct timespec time_start, time_run1, time_reset, time_run2, time_ro;
 	uint64_t max_gpa, gpa, slot_size, max_mem, i;
 	int max_slots, slot, opt, fd;
 	bool hugepages = false;
@@ -279,14 +287,20 @@ int main(int argc, char *argv[])
 	rendezvous_with_vcpus(&time_reset, "reset");
 	rendezvous_with_vcpus(&time_run2, "run 2");
 
+	mprotect(mem, slot_size, PROT_READ);
+	rendezvous_with_vcpus(&time_ro, "mprotect RO");
+
+	time_ro    = timespec_sub(time_ro,     time_run2);
 	time_run2  = timespec_sub(time_run2,   time_reset);
-	time_reset = timespec_sub(time_reset, time_run1);
+	time_reset = timespec_sub(time_reset,  time_run1);
 	time_run1  = timespec_sub(time_run1,   time_start);
 
-	pr_info("run1 = %ld.%.9lds, reset = %ld.%.9lds, run2 =  %ld.%.9lds\n",
+	pr_info("run1 = %ld.%.9lds, reset = %ld.%.9lds, run2 = %ld.%.9lds, "
+		"ro = %ld.%.9lds\n",
 		time_run1.tv_sec, time_run1.tv_nsec,
 		time_reset.tv_sec, time_reset.tv_nsec,
-		time_run2.tv_sec, time_run2.tv_nsec);
+		time_run2.tv_sec, time_run2.tv_nsec,
+		time_ro.tv_sec, time_ro.tv_nsec);
 
 	/*
 	 * Delete even numbered slots (arbitrary) and unmap the first half of
-- 
2.47.0.338.g60cca15819-goog