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[SRU,N:intel,4/4] KVM: selftests: x86: Prioritize getting max_gfn from GuestPhysBits

Message ID 20240704162521.3375266-5-thibault.ferrante@canonical.com
State New
Headers show
Series Fix QEMU/KVM support for EPT paging level 4/5 | expand

Commit Message

Thibault Ferrante July 4, 2024, 4:25 p.m. UTC 
From: Tao Su <tao1.su@linux.intel.com>

BugLink: https://bugs.launchpad.net/bugs/2071628

Use the max mappable GPA via GuestPhysBits advertised by KVM to calculate
max_gfn. Currently some selftests (e.g. access_tracking_perf_test,
dirty_log_test...) add RAM regions close to max_gfn, so guest may access
GPA beyond its mappable range and cause infinite loop.

Adjust max_gfn in vm_compute_max_gfn() since x86 selftests already
overrides vm_compute_max_gfn() specifically to deal with goofy edge cases.

Reported-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Tao Su <tao1.su@linux.intel.com>
Tested-by: Yi Lai <yi1.lai@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20240513014003.104593-1-tao1.su@linux.intel.com
[sean: tweak name, add comment and sanity check]
Signed-off-by: Sean Christopherson <seanjc@google.com>
(cherry picked from commit 980b8bc01938c8bcc9742c1051f64b5f0ed178ac)
Signed-off-by: Thibault Ferrante <thibault.ferrante@canonical.com>
---
 .../selftests/kvm/include/x86_64/processor.h      |  1 +
 .../testing/selftests/kvm/lib/x86_64/processor.c  | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index d2534a4a077b..3142eb4f05e3 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -279,6 +279,7 @@  struct kvm_x86_cpu_property {
 #define X86_PROPERTY_MAX_EXT_LEAF		KVM_X86_CPU_PROPERTY(0x80000000, 0, EAX, 0, 31)
 #define X86_PROPERTY_MAX_PHY_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 0, 7)
 #define X86_PROPERTY_MAX_VIRT_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 8, 15)
+#define X86_PROPERTY_GUEST_MAX_PHY_ADDR		KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
 #define X86_PROPERTY_SEV_C_BIT			KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 0, 5)
 #define X86_PROPERTY_PHYS_ADDR_REDUCTION	KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
 
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 4b7fe7e1e234..832f85dcf269 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1278,9 +1278,20 @@  unsigned long vm_compute_max_gfn(struct kvm_vm *vm)
 {
 	const unsigned long num_ht_pages = 12 << (30 - vm->page_shift); /* 12 GiB */
 	unsigned long ht_gfn, max_gfn, max_pfn;
-	uint8_t maxphyaddr;
+	uint8_t maxphyaddr, guest_maxphyaddr;
 
-	max_gfn = (1ULL << (vm->pa_bits - vm->page_shift)) - 1;
+	/*
+	 * Use "guest MAXPHYADDR" from KVM if it's available.  Guest MAXPHYADDR
+	 * enumerates the max _mappable_ GPA, which can be less than the raw
+	 * MAXPHYADDR, e.g. if MAXPHYADDR=52, KVM is using TDP, and the CPU
+	 * doesn't support 5-level TDP.
+	 */
+	guest_maxphyaddr = kvm_cpu_property(X86_PROPERTY_GUEST_MAX_PHY_ADDR);
+	guest_maxphyaddr = guest_maxphyaddr ?: vm->pa_bits;
+	TEST_ASSERT(guest_maxphyaddr <= vm->pa_bits,
+		    "Guest MAXPHYADDR should never be greater than raw MAXPHYADDR");
+
+	max_gfn = (1ULL << (guest_maxphyaddr - vm->page_shift)) - 1;
 
 	/* Avoid reserved HyperTransport region on AMD processors.  */
 	if (!host_cpu_is_amd)