[PATCH v7 0/4] KVM: SEV-ES: Add tests to validate #VC handling

[PATCH v7 0/4] KVM: SEV-ES: Add tests to validate #VC handling

[Vasant Karasulli]

Hi All,

   This is the version 7 of the patch written to add tests for
   AMD SEV-ES #VC handling. This version attempts to
   address review comments to the previous version of the patch.

   Changes v6->v7:
   1. Added information about how to run the tests.
   2. test->priv no longer points to a location on heap.

Thanks,
Vasant

 arch/x86/Kbuild              |   2 +
 arch/x86/Kconfig.debug       |  19 +++++
 arch/x86/kernel/Makefile     |   7 ++
 arch/x86/tests/Makefile      |   3 +
 arch/x86/tests/sev-test-vc.c | 145 +++++++++++++++++++++++++++++++++++
 5 files changed, 176 insertions(+)
 create mode 100644 arch/x86/tests/Makefile
 create mode 100644 arch/x86/tests/sev-test-vc.c


base-commit: b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3
--
2.32.0

[PATCH v7 1/4] KVM: SEV-ES: Add configuration options to test #VC handling

[Vasant Karasulli]

Configuration options CONFIG_X86_TESTS and CONFIG_AMD_SEV_ES_TEST_VC
enable the execution of the KUnit tests added under arch/x86/tests that
test AMD SEV-ES #VC handling.

Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 arch/x86/Kbuild          |  2 ++
 arch/x86/Kconfig.debug   | 19 +++++++++++++++++++
 arch/x86/kernel/Makefile |  7 +++++++
 3 files changed, 28 insertions(+)

diff --git a/arch/x86/Kbuild b/arch/x86/Kbuild
index 5a83da703e87..ec01cd024bae 100644
--- a/arch/x86/Kbuild
+++ b/arch/x86/Kbuild
@@ -28,5 +28,7 @@ obj-y += net/

 obj-$(CONFIG_KEXEC_FILE) += purgatory/

+obj-y += tests/
+
 # for cleaning
 subdir- += boot tools
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 340399f69954..b0687173fb97 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -278,3 +278,22 @@ endchoice
 config FRAME_POINTER
 	depends on !UNWINDER_ORC && !UNWINDER_GUESS
 	bool
+
+config X86_TESTS
+	bool "x86 unit tests"
+	help
+	    This enables building the tests under arch/x86/tests.
+
+if X86_TESTS
+config AMD_SEV_TEST_VC
+	bool "Test for AMD SEV VC exception handling"
+	depends on AMD_MEM_ENCRYPT
+	select FUNCTION_TRACER
+	select KPROBES
+	select KUNIT
+	help
+	  Enable KUnit-based testing for AMD SEV #VC exception handling.
+	  When this configuration option is enabled, these Kunit tests
+	  get executed at the kernel boot time. Results of the test
+	  execution can be monitored in the kernel log.
+endif # X86_TESTS
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 03364dc40d8d..3fa9ce2a700e 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -23,6 +23,13 @@ CFLAGS_REMOVE_head64.o = -pg
 CFLAGS_REMOVE_sev.o = -pg
 endif

+# AMD_SEV_TEST_VC registers a kprobe by function name. IPA-SRA creates
+# function copies and renames them to have an .isra suffix, which breaks kprobes'
+# lookup. Build with -fno-ipa-sra for the test.
+ifdef CONFIG_AMD_SEV_TEST_VC
+CFLAGS_sev.o	+= -fno-ipa-sra
+endif
+
 KASAN_SANITIZE_head$(BITS).o				:= n
 KASAN_SANITIZE_dumpstack.o				:= n
 KASAN_SANITIZE_dumpstack_$(BITS).o			:= n
--
2.32.0

[PATCH v7 2/4] KVM: SEV-ES: Add tests to validate VC handling for CPUID and WBINVD

[Vasant Karasulli]

These tests:
     1. install a kretprobe on the #VC handler (sev_es_ghcb_hv_call, to
        access GHCB before/after the resulting VMGEXIT).
     2. trigger an NAE by executing either CPUID or WBINVD.
     3. check that the kretprobe was hit with the right exit_code
        available in GHCB.

To run these tests, configuration options CONFIG_X86_TESTS and
CONFIG_AMD_SEV_ES_TEST_VC have to be enabled. These tests run
at the kernel boot time. Result of the test execution can be
monitored in the kernel log.

Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 arch/x86/tests/Makefile      |   3 +
 arch/x86/tests/sev-test-vc.c | 104 +++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 arch/x86/tests/Makefile
 create mode 100644 arch/x86/tests/sev-test-vc.c

diff --git a/arch/x86/tests/Makefile b/arch/x86/tests/Makefile
new file mode 100644
index 000000000000..4beca64bd2aa
--- /dev/null
+++ b/arch/x86/tests/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_AMD_SEV_TEST_VC)	+= sev-test-vc.o
diff --git a/arch/x86/tests/sev-test-vc.c b/arch/x86/tests/sev-test-vc.c
new file mode 100644
index 000000000000..900ca357a273
--- /dev/null
+++ b/arch/x86/tests/sev-test-vc.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 SUSE
+ *
+ * Author: Varad Gautam <varad.gautam@suse.com>
+ */
+
+#include <asm/cpufeature.h>
+#include <asm/sev-common.h>
+#include <asm/svm.h>
+#include <kunit/test.h>
+#include <linux/kprobes.h>
+
+static struct kretprobe hv_call_krp;
+
+static int hv_call_krp_entry(struct kretprobe_instance *krpi,
+			     struct pt_regs *regs)
+{
+	unsigned long ghcb_vaddr = regs_get_kernel_argument(regs, 0);
+	*((unsigned long *) krpi->data) = ghcb_vaddr;
+
+	return 0;
+}
+
+static int hv_call_krp_ret(struct kretprobe_instance *krpi,
+			   struct pt_regs *regs)
+{
+	unsigned long ghcb_vaddr = *((unsigned long *) krpi->data);
+	struct ghcb *ghcb = (struct ghcb *) ghcb_vaddr;
+	struct kunit *test = current->kunit_test;
+
+	if (test && strstr(test->name, "sev_es_"))
+		*((u64 *)&test->priv) = ghcb->save.sw_exit_code;
+
+	return 0;
+}
+
+int sev_es_test_vc_init(struct kunit *test)
+{
+	int ret;
+
+	if (!cc_platform_has(CC_ATTR_GUEST_STATE_ENCRYPT)) {
+		kunit_info(test, "Not a SEV-ES guest. Skipping.");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	memset(&hv_call_krp, 0, sizeof(hv_call_krp));
+	hv_call_krp.entry_handler = hv_call_krp_entry;
+	hv_call_krp.handler = hv_call_krp_ret;
+	hv_call_krp.maxactive = 100;
+	hv_call_krp.data_size = sizeof(unsigned long);
+	hv_call_krp.kp.symbol_name = "sev_es_ghcb_hv_call";
+	hv_call_krp.kp.addr = 0;
+
+	ret = register_kretprobe(&hv_call_krp);
+	if (ret) {
+		kunit_info(test, "Could not register kretprobe. Skipping.");
+		goto out;
+	}
+
+out:
+	return ret;
+}
+
+void sev_es_test_vc_exit(struct kunit *test)
+{
+	if (hv_call_krp.kp.addr)
+		unregister_kretprobe(&hv_call_krp);
+}
+
+#define check_op(kt, ec, op)			        \
+do {						        \
+	struct kunit *t = (struct kunit *) kt;	        \
+	op;					        \
+	KUNIT_EXPECT_EQ(t, (typeof(ec)) ec,	        \
+			((typeof(ec))((u64)(t->priv))));\
+} while (0)
+
+static void sev_es_nae_cpuid(struct kunit *test)
+{
+	unsigned int cpuid_fn = 0x8000001f;
+
+	check_op(test, SVM_EXIT_CPUID, native_cpuid_eax(cpuid_fn));
+}
+
+static void sev_es_nae_wbinvd(struct kunit *test)
+{
+	check_op(test, SVM_EXIT_WBINVD, wbinvd());
+}
+
+static struct kunit_case sev_es_vc_testcases[] = {
+	KUNIT_CASE(sev_es_nae_cpuid),
+	KUNIT_CASE(sev_es_nae_wbinvd),
+	{}
+};
+
+static struct kunit_suite sev_es_vc_test_suite = {
+	.name = "sev_es_test_vc",
+	.init = sev_es_test_vc_init,
+	.exit = sev_es_test_vc_exit,
+	.test_cases = sev_es_vc_testcases,
+};
+kunit_test_suite(sev_es_vc_test_suite);
--
2.32.0

[PATCH v7 3/4] KVM: SEV-ES: Add tests to validate VC handling for MSR and DR7 register accesses

[Vasant Karasulli]

These tests:
   1. install a kretprobe on the #VC handler (sev_es_ghcb_hv_call, to
       access GHCB before/after the resulting VMGEXIT).
   2. trigger an NAE by accessing either MSR or DR7.
   3. check that the kretprobe was hit with the right exit_code available
      in GHCB.

To run these tests, configuration options CONFIG_X86_TESTS and
CONFIG_AMD_SEV_ES_TEST_VC have to be enabled. These tests run
at the kernel boot time. Result of the test execution can be
monitored in the kernel log.

Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 arch/x86/tests/sev-test-vc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/tests/sev-test-vc.c b/arch/x86/tests/sev-test-vc.c
index 900ca357a273..629aa0ca1c86 100644
--- a/arch/x86/tests/sev-test-vc.c
+++ b/arch/x86/tests/sev-test-vc.c
@@ -7,6 +7,7 @@

 #include <asm/cpufeature.h>
 #include <asm/sev-common.h>
+#include <asm/debugreg.h>
 #include <asm/svm.h>
 #include <kunit/test.h>
 #include <linux/kprobes.h>
@@ -89,9 +90,22 @@ static void sev_es_nae_wbinvd(struct kunit *test)
 	check_op(test, SVM_EXIT_WBINVD, wbinvd());
 }

+static void sev_es_nae_msr(struct kunit *test)
+{
+	check_op(test, SVM_EXIT_MSR, __rdmsr(MSR_IA32_TSC));
+}
+
+static void sev_es_nae_dr7_rw(struct kunit *test)
+{
+	check_op(test, SVM_EXIT_WRITE_DR7,
+		   native_set_debugreg(7, native_get_debugreg(7)));
+}
+
 static struct kunit_case sev_es_vc_testcases[] = {
 	KUNIT_CASE(sev_es_nae_cpuid),
 	KUNIT_CASE(sev_es_nae_wbinvd),
+	KUNIT_CASE(sev_es_nae_msr),
+	KUNIT_CASE(sev_es_nae_dr7_rw),
 	{}
 };

--
2.32.0

[PATCH v7 4/4] KVM SEV-ES: Add tests to validate VC handling for IO instructions

[Vasant Karasulli]

These tests:
   1. install a kretprobe on the #VC handler (sev_es_ghcb_hv_call, to
      access GHCB before/after the resulting VMGEXIT).
   2. trigger an NAE by issuing an IO instruction.
   3. check that the kretprobe was hit with the right
      exit_code available in GHCB.

To run these tests, configuration options CONFIG_X86_TESTS and
CONFIG_AMD_SEV_ES_TEST_VC have to be enabled. These tests run
at the kernel boot time. Result of the test execution can be
monitored in the kernel log.

Signed-off-by: Vasant Karasulli <vkarasulli@suse.de>
---
 arch/x86/tests/sev-test-vc.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/arch/x86/tests/sev-test-vc.c b/arch/x86/tests/sev-test-vc.c
index 629aa0ca1c86..33ca761bf9cb 100644
--- a/arch/x86/tests/sev-test-vc.c
+++ b/arch/x86/tests/sev-test-vc.c
@@ -8,7 +8,9 @@
 #include <asm/cpufeature.h>
 #include <asm/sev-common.h>
 #include <asm/debugreg.h>
+#include <asm/io.h>
 #include <asm/svm.h>
+#include <asm/apicdef.h>
 #include <kunit/test.h>
 #include <linux/kprobes.h>

@@ -101,11 +103,36 @@ static void sev_es_nae_dr7_rw(struct kunit *test)
 		   native_set_debugreg(7, native_get_debugreg(7)));
 }

+static void sev_es_nae_ioio(struct kunit *test)
+{
+	unsigned long port = 0x80;
+	char val = 0;
+
+	check_op(test, SVM_EXIT_IOIO, val = inb(port));
+	check_op(test, SVM_EXIT_IOIO, outb(val, port));
+	check_op(test, SVM_EXIT_IOIO, insb(port, &val, sizeof(val)));
+	check_op(test, SVM_EXIT_IOIO, outsb(port, &val, sizeof(val)));
+}
+
+static void sev_es_nae_mmio(struct kunit *test)
+{
+	unsigned long lapic_ver_pa = APIC_DEFAULT_PHYS_BASE + APIC_LVR;
+	unsigned long __iomem *lapic = ioremap(lapic_ver_pa, 0x4);
+	unsigned long lapic_version = 0;
+
+	check_op(test, SVM_VMGEXIT_MMIO_READ, lapic_version = *lapic);
+	check_op(test, SVM_VMGEXIT_MMIO_WRITE, *lapic = lapic_version);
+
+	iounmap(lapic);
+}
+
 static struct kunit_case sev_es_vc_testcases[] = {
 	KUNIT_CASE(sev_es_nae_cpuid),
 	KUNIT_CASE(sev_es_nae_wbinvd),
 	KUNIT_CASE(sev_es_nae_msr),
 	KUNIT_CASE(sev_es_nae_dr7_rw),
+	KUNIT_CASE(sev_es_nae_ioio),
+	KUNIT_CASE(sev_es_nae_mmio),
 	{}
 };

--
2.32.0