Excerise nested VMX's atomic MSR switch code (e.g., VM-entry MSR-load
list) at the maximum number of MSRs supported, as described in the SDM,
in the appendix chapter titled "MISCELLANEOUS DATA".
Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Marc Orr <marcorr@xxxxxxxxxx>
---
v4 -> v5
* Replaced local pointer declarations for MSR lists with existing global
declarations.
* Replaced atomic_switch_msr_limit_test_guest() with existing vmcall()
funciton.
* Removed redundant assert_exit_reason(VMX_VMCALL).
lib/alloc_page.c | 5 ++
lib/alloc_page.h | 1 +
x86/unittests.cfg | 2 +-
x86/vmx_tests.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 141 insertions(+), 1 deletion(-)
diff --git a/lib/alloc_page.c b/lib/alloc_page.c
index 97d13395ff08..ed236389537e 100644
--- a/lib/alloc_page.c
+++ b/lib/alloc_page.c
@@ -53,6 +53,11 @@ void free_pages(void *mem, unsigned long size)
spin_unlock(&lock);
}
+void free_pages_by_order(void *mem, unsigned long order)
+{
+ free_pages(mem, 1ul << (order + PAGE_SHIFT));
+}
+
void *alloc_page()
{
void *p;
diff --git a/lib/alloc_page.h b/lib/alloc_page.h
index 5cdfec57a0a8..739a91def979 100644
--- a/lib/alloc_page.h
+++ b/lib/alloc_page.h
@@ -14,5 +14,6 @@ void *alloc_page(void);
void *alloc_pages(unsigned long order);
void free_page(void *page);
void free_pages(void *mem, unsigned long size);
+void free_pages_by_order(void *mem, unsigned long order);
#endif
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index 694ee3d42f3a..05122cf91ea1 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -227,7 +227,7 @@ extra_params = -cpu qemu64,+umip
[vmx]
file = vmx.flat
-extra_params = -cpu host,+vmx -append "-exit_monitor_from_l2_test -ept_access* -vmx_smp* -vmx_vmcs_shadow_test"
+extra_params = -cpu host,+vmx -append "-exit_monitor_from_l2_test -ept_access* -vmx_smp* -vmx_vmcs_shadow_test -atomic_switch_overflow_msrs_test"
arch = x86_64
groups = vmx
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index f035f24a771a..cc33ea7b5114 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8570,6 +8570,137 @@ static int invalid_msr_entry_failure(struct vmentry_failure *failure)
return VMX_TEST_VMEXIT;
}
+/*
+ * The max number of MSRs in an atomic switch MSR list is:
+ * (111B + 1) * 512 = 4096
+ *
+ * Each list entry consumes:
+ * 4-byte MSR index + 4 bytes reserved + 8-byte data = 16 bytes
+ *
+ * Allocate 128 kB to cover max_msr_list_size (i.e., 64 kB) and then some.
+ */
+static const u32 msr_list_page_order = 5;
+
+static void atomic_switch_msr_limit_test_guest(void)
+{
+ vmcall();
+}
+
+static void populate_msr_list(struct vmx_msr_entry *msr_list,
+ size_t byte_capacity, int count)
+{
+ int i;
+
+ for (i = 0; i < count; i++) {
+ msr_list[i].index = MSR_IA32_TSC;
+ msr_list[i].reserved = 0;
+ msr_list[i].value = 0x1234567890abcdef;
+ }
+
+ memset(msr_list + count, 0xff,
+ byte_capacity - count * sizeof(*msr_list));
+}
+
+static int max_msr_list_size(void)
+{
+ u32 vmx_misc = rdmsr(MSR_IA32_VMX_MISC);
+ u32 factor = ((vmx_misc & GENMASK(27, 25)) >> 25) + 1;
+
+ return factor * 512;
+}
+
+static void atomic_switch_msrs_test(int count)
+{
+ struct vmx_msr_entry *vm_enter_load;
+ struct vmx_msr_entry *vm_exit_load;
+ struct vmx_msr_entry *vm_exit_store;
+ int max_allowed = max_msr_list_size();
+ int byte_capacity = 1ul << (msr_list_page_order + PAGE_SHIFT);
+ /* KVM signals VM-Abort if an exit MSR list exceeds the max size. */
+ int exit_count = MIN(count, max_allowed);
+
+ /*
+ * Check for the IA32_TSC MSR,
+ * available with the "TSC flag" and used to populate the MSR lists.
+ */
+ if (!(cpuid(1).d & (1 << 4))) {
+ report_skip(__func__);
+ return;
+ }
+
+ /* Set L2 guest. */
+ test_set_guest(atomic_switch_msr_limit_test_guest);
+
+ /* Setup atomic MSR switch lists. */
+ vm_enter_load = alloc_pages(msr_list_page_order);
+ vm_exit_load = alloc_pages(msr_list_page_order);
+ vm_exit_store = alloc_pages(msr_list_page_order);
+
+ vmcs_write(ENTER_MSR_LD_ADDR, (u64)vm_enter_load);
+ vmcs_write(EXIT_MSR_LD_ADDR, (u64)vm_exit_load);
+ vmcs_write(EXIT_MSR_ST_ADDR, (u64)vm_exit_store);
+
+ /*
+ * VM-Enter should succeed up to the max number of MSRs per list, and
+ * should not consume junk beyond the last entry.
+ */
+ populate_msr_list(vm_enter_load, byte_capacity, count);
+ populate_msr_list(vm_exit_load, byte_capacity, exit_count);
+ populate_msr_list(vm_exit_store, byte_capacity, exit_count);
+
+ vmcs_write(ENT_MSR_LD_CNT, count);
+ vmcs_write(EXI_MSR_LD_CNT, exit_count);
+ vmcs_write(EXI_MSR_ST_CNT, exit_count);
+
+ if (count <= max_allowed) {
+ enter_guest();
+ assert_exit_reason(VMX_VMCALL);
+ skip_exit_vmcall();
+ } else {
+ u32 exit_reason;
+ u32 exit_reason_want;
+ u32 exit_qual;
+
+ enter_guest_with_invalid_guest_state();
+
+ exit_reason = vmcs_read(EXI_REASON);
+ exit_reason_want = VMX_FAIL_MSR | VMX_ENTRY_FAILURE;
+ report("exit_reason, %u, is %u.",
+ exit_reason == exit_reason_want, exit_reason,
+ exit_reason_want);
+
+ exit_qual = vmcs_read(EXI_QUALIFICATION);
+ report("exit_qual, %u, is %u.", exit_qual == max_allowed + 1,
+ exit_qual, max_allowed + 1);
+
+ /*
+ * Re-enter the guest with valid counts
+ * and proceed past the single vmcall instruction.
+ */
+ vmcs_write(ENT_MSR_LD_CNT, 0);
+ vmcs_write(EXI_MSR_LD_CNT, 0);
+ vmcs_write(EXI_MSR_ST_CNT, 0);
+ enter_guest();
+ skip_exit_vmcall();
+ }
+
+ /* Cleanup. */
+ enter_guest();
+ skip_exit_vmcall();
+ free_pages_by_order(vm_enter_load, msr_list_page_order);
+ free_pages_by_order(vm_exit_load, msr_list_page_order);
+ free_pages_by_order(vm_exit_store, msr_list_page_order);
+}
+
+static void atomic_switch_max_msrs_test(void)
+{
+ atomic_switch_msrs_test(max_msr_list_size());
+}
+
+static void atomic_switch_overflow_msrs_test(void)
+{
+ atomic_switch_msrs_test(max_msr_list_size() + 1);
+}
#define TEST(name) { #name, .v2 = name }
@@ -8660,5 +8791,8 @@ struct vmx_test vmx_tests[] = {
TEST(ept_access_test_paddr_read_execute_ad_enabled),
TEST(ept_access_test_paddr_not_present_page_fault),
TEST(ept_access_test_force_2m_page),
+ /* Atomic MSR switch tests. */
+ TEST(atomic_switch_max_msrs_test),
+ TEST(atomic_switch_overflow_msrs_test),
{ NULL, NULL, NULL, NULL, NULL, {0} },
};
