[kvm-unit-tests PATCH v6 1/2] x86: nvmx: fix bug in __enter_guest()

[kvm-unit-tests PATCH v6 1/2] x86: nvmx: fix bug in __enter_guest()

[Marc Orr]

__enter_guest() should only set the launched flag when a launch has
succeeded. Thus, don't set the launched flag when the VMX_ENTRY_FAILURE,
bit 31, is set in the VMCS exit reason.

Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Marc Orr <marcorr@google.com>
---
v5 -> v6
* No changes.

 x86/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/x86/vmx.c b/x86/vmx.c
index 6079420db33a..7313c78f15c2 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -1820,7 +1820,7 @@ static void __enter_guest(u8 abort_flag, struct vmentry_failure *failure)
 		abort();
 	}
 
-	if (!failure->early) {
+	if (!failure->early && !(vmcs_read(EXI_REASON) & VMX_ENTRY_FAILURE)) {
 		launched = 1;
 		check_for_guest_termination();
 	}
-- 
2.23.0.351.gc4317032e6-goog

[kvm-unit-tests PATCH v6 2/2] x86: nvmx: test max atomic switch MSRs

[Marc Orr]

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@google.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: Marc Orr <marcorr@google.com>
---
v5 -> v6
* Replaced atomic_switch_msr_limit_test_guest() (which was supposed to
 vmcall() in v5!) w/ v2_null_test_guest() and updated exit handling
 logic accordingly.

 lib/alloc_page.c  |   5 ++
 lib/alloc_page.h  |   1 +
 x86/unittests.cfg |   2 +-
 x86/vmx_tests.c   | 123 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 130 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..f8ee0f0f8f2b 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8570,6 +8570,126 @@ 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 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)
+{
+	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(v2_null_test_guest);
+
+	/* Setup atomic MSR switch lists. */
+	entry_msr_load = alloc_pages(msr_list_page_order);
+	exit_msr_load = alloc_pages(msr_list_page_order);
+	exit_msr_store = alloc_pages(msr_list_page_order);
+
+	vmcs_write(ENTER_MSR_LD_ADDR, (u64)entry_msr_load);
+	vmcs_write(EXIT_MSR_LD_ADDR, (u64)exit_msr_load);
+	vmcs_write(EXIT_MSR_ST_ADDR, (u64)exit_msr_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(entry_msr_load, byte_capacity, count);
+	populate_msr_list(exit_msr_load, byte_capacity, exit_count);
+	populate_msr_list(exit_msr_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() verifies that VM-enter succeeds. After the
+		 * test completes, the test harness (see test_run() in vmx.c)
+		 * verifies that the VM-enter completes by reaching the end of
+		 * v2_null_test_guest().
+		 */
+		enter_guest();
+	} 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);
+
+		/* Enter the guest (with valid counts) to set guest_finished. */
+		vmcs_write(ENT_MSR_LD_CNT, 0);
+		vmcs_write(EXI_MSR_LD_CNT, 0);
+		vmcs_write(EXI_MSR_ST_CNT, 0);
+		enter_guest();
+	}
+
+	free_pages_by_order(entry_msr_load, msr_list_page_order);
+	free_pages_by_order(exit_msr_load, msr_list_page_order);
+	free_pages_by_order(exit_msr_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 +8780,8 @@ 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} },
 };
-- 
2.23.0.351.gc4317032e6-goog

Re: [kvm-unit-tests PATCH v6 2/2] x86: nvmx: test max atomic switch MSRs

[Sean Christopherson]

On Fri, Sep 20, 2019 at 03:29:45PM -0700, Marc Orr wrote:
> +		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);

I'd stick with the more standard "val %u, expected %u" verbiage.  E.g.:

	exit_reason, 34, is 35

versus

	exit_reason 34, expected 35

The "is" part makes it sound like the value in the VMCS *is* 35.

Re: [kvm-unit-tests PATCH v6 2/2] x86: nvmx: test max atomic switch MSRs

[Marc Orr]

On Mon, Sep 23, 2019 at 1:08 PM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> On Fri, Sep 20, 2019 at 03:29:45PM -0700, Marc Orr wrote:
> > +             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);
>
> I'd stick with the more standard "val %u, expected %u" verbiage.  E.g.:
>
>         exit_reason, 34, is 35
>
> versus
>
>         exit_reason 34, expected 35
>
> The "is" part makes it sound like the value in the VMCS *is* 35.

Done.