[PATCH 11/11] KVM: selftests: Add test to verify KVM handles x2APIC ICR=>ICR2 dance
From: Sean Christopherson
Date: Fri Feb 04 2022 - 16:43:08 EST
Add a selftest to verify that KVM copies x2APIC's ICR[63:32] to/from
ICR2 when userspace accesses the vAPIC page via KVM_{G,S}ET_LAPIC. KVM
previously split x2APIC ICR to ICR+ICR2 at the time of write (from the
guest), and so KVM must preserve that behavior for backwards
compatibility between different versions of KVM.
Opportunsitically test other invariants, e.g. that KVM clears the BUSY
flag on ICR writes, that the reserved bits in ICR2 are dropped on writes
from the guest, etc...
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/apic.h | 1 +
.../selftests/kvm/x86_64/xapic_state_test.c | 150 ++++++++++++++++++
4 files changed, 153 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/xapic_state_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index dce7de7755e6..2b0e47f420b3 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -45,6 +45,7 @@
/x86_64/vmx_tsc_adjust_test
/x86_64/vmx_nested_tsc_scaling_test
/x86_64/xapic_ipi_test
+/x86_64/xapic_state_test
/x86_64/xen_shinfo_test
/x86_64/xen_vmcall_test
/x86_64/xss_msr_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 0e4926bc9a58..4b5211afc6dc 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -76,6 +76,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_tsc_adjust_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_nested_tsc_scaling_test
TEST_GEN_PROGS_x86_64 += x86_64/xapic_ipi_test
+TEST_GEN_PROGS_x86_64 += x86_64/xapic_state_test
TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
TEST_GEN_PROGS_x86_64 += x86_64/debug_regs
TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test
diff --git a/tools/testing/selftests/kvm/include/x86_64/apic.h b/tools/testing/selftests/kvm/include/x86_64/apic.h
index 0be4757f1f20..ac88557dcc9a 100644
--- a/tools/testing/selftests/kvm/include/x86_64/apic.h
+++ b/tools/testing/selftests/kvm/include/x86_64/apic.h
@@ -33,6 +33,7 @@
#define APIC_SPIV 0xF0
#define APIC_SPIV_FOCUS_DISABLED (1 << 9)
#define APIC_SPIV_APIC_ENABLED (1 << 8)
+#define APIC_IRR 0x200
#define APIC_ICR 0x300
#define APIC_DEST_SELF 0x40000
#define APIC_DEST_ALLINC 0x80000
diff --git a/tools/testing/selftests/kvm/x86_64/xapic_state_test.c b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
new file mode 100644
index 000000000000..0792334ba243
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/xapic_state_test.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "apic.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+struct kvm_vcpu {
+ uint32_t id;
+ bool is_x2apic;
+};
+
+static void xapic_guest_code(void)
+{
+ asm volatile("cli");
+
+ xapic_enable();
+
+ while (1) {
+ uint64_t val = (u64)xapic_read_reg(APIC_IRR) |
+ (u64)xapic_read_reg(APIC_IRR + 0x10) << 32;
+
+ xapic_write_reg(APIC_ICR2, val >> 32);
+ xapic_write_reg(APIC_ICR, val);
+ GUEST_SYNC(val);
+ }
+}
+
+static void x2apic_guest_code(void)
+{
+ asm volatile("cli");
+
+ x2apic_enable();
+
+ do {
+ uint64_t val = x2apic_read_reg(APIC_IRR) |
+ x2apic_read_reg(APIC_IRR + 0x10) << 32;
+
+ x2apic_write_reg(APIC_ICR, val);
+ GUEST_SYNC(val);
+ } while (1);
+}
+
+static void ____test_icr(struct kvm_vm *vm, struct kvm_vcpu *vcpu, uint64_t val)
+{
+ struct kvm_lapic_state xapic;
+ struct ucall uc;
+ uint64_t icr;
+
+ /*
+ * Tell the guest what ICR value to write. Use the IRR to pass info,
+ * all bits are valid and should not be modified by KVM (ignoring the
+ * fact that vectors 0-15 are technically illegal).
+ */
+ vcpu_ioctl(vm, vcpu->id, KVM_GET_LAPIC, &xapic);
+ *((u32 *)&xapic.regs[APIC_IRR]) = val;
+ *((u32 *)&xapic.regs[APIC_IRR + 0x10]) = val >> 32;
+ vcpu_ioctl(vm, vcpu->id, KVM_SET_LAPIC, &xapic);
+
+ vcpu_run(vm, vcpu->id);
+ ASSERT_EQ(get_ucall(vm, vcpu->id, &uc), UCALL_SYNC);
+ ASSERT_EQ(uc.args[1], val);
+
+ vcpu_ioctl(vm, vcpu->id, KVM_GET_LAPIC, &xapic);
+ icr = (u64)(*((u32 *)&xapic.regs[APIC_ICR])) |
+ (u64)(*((u32 *)&xapic.regs[APIC_ICR2])) << 32;
+ if (!vcpu->is_x2apic)
+ val &= (-1u | (0xffull << (32 + 24)));
+ ASSERT_EQ(icr, val & ~APIC_ICR_BUSY);
+}
+
+static void __test_icr(struct kvm_vm *vm, struct kvm_vcpu *vcpu, uint64_t val)
+{
+ ____test_icr(vm, vcpu, val | APIC_ICR_BUSY);
+ ____test_icr(vm, vcpu, val & ~(u64)APIC_ICR_BUSY);
+}
+
+static void test_icr(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+ uint64_t icr, i, j;
+
+ icr = APIC_DEST_SELF | APIC_INT_ASSERT | APIC_DM_FIXED;
+ for (i = 0; i <= 0xff; i++)
+ __test_icr(vm, vcpu, icr | i);
+
+ icr = APIC_INT_ASSERT | APIC_DM_FIXED;
+ for (i = 0; i <= 0xff; i++)
+ __test_icr(vm, vcpu, icr | i);
+
+ /*
+ * Send all flavors of IPIs to non-existent vCPUs. TODO: use number of
+ * vCPUs, not vcpu.id + 1. Arbitrarily use vector 0xff.
+ */
+ icr = APIC_INT_ASSERT | 0xff;
+ for (i = vcpu->id + 1; i < 0xff; i++) {
+ for (j = 0; j < 8; j++)
+ __test_icr(vm, vcpu, i << (32 + 24) | APIC_INT_ASSERT | (j << 8));
+ }
+
+ /* And again with a shorthand destination for all types of IPIs. */
+ icr = APIC_DEST_ALLBUT | APIC_INT_ASSERT;
+ for (i = 0; i < 8; i++)
+ __test_icr(vm, vcpu, icr | (i << 8));
+
+ /* And a few garbage value, just make sure it's an IRQ (blocked). */
+ __test_icr(vm, vcpu, 0xa5a5a5a5a5a5a5a5 & ~APIC_DM_FIXED_MASK);
+ __test_icr(vm, vcpu, 0x5a5a5a5a5a5a5a5a & ~APIC_DM_FIXED_MASK);
+ __test_icr(vm, vcpu, -1ull & ~APIC_DM_FIXED_MASK);
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_vcpu vcpu = {
+ .id = 0,
+ .is_x2apic = true,
+ };
+ struct kvm_cpuid2 *cpuid;
+ struct kvm_vm *vm;
+ int i;
+
+ vm = vm_create_default(vcpu.id, 0, x2apic_guest_code);
+ test_icr(vm, &vcpu);
+ kvm_vm_free(vm);
+
+ /*
+ * Use a second VM for the xAPIC test so that x2APIC can be hidden from
+ * the guest in order to test AVIC. KVM disallows changing CPUID after
+ * KVM_RUN and AVIC is disabled if _any_ vCPU is allowed to use x2APIC.
+ */
+ vm = vm_create_default(vcpu.id, 0, xapic_guest_code);
+ vcpu.is_x2apic = false;
+
+ cpuid = vcpu_get_cpuid(vm, vcpu.id);
+ for (i = 0; i < cpuid->nent; i++) {
+ if (cpuid->entries[i].function == 1)
+ break;
+ }
+ cpuid->entries[i].ecx &= ~BIT(21);
+ vcpu_set_cpuid(vm, vcpu.id, cpuid);
+
+ virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
+ test_icr(vm, &vcpu);
+ kvm_vm_free(vm);
+}
--
2.35.0.263.gb82422642f-goog