* [PATCH v2 3/4] selftests: kvm: Add exception handling to selftests
2020-10-09 11:46 [PATCH v2 0/4] Test MSR exits to userspace Aaron Lewis
2020-10-09 11:46 ` [PATCH v2 1/4] selftests: kvm: Fix the segment descriptor layout to match the actual layout Aaron Lewis
2020-10-09 11:46 ` [PATCH v2 2/4] selftests: kvm: Clear uc so UCALL_NONE is being properly reported Aaron Lewis
@ 2020-10-09 11:46 ` Aaron Lewis
2020-10-09 12:38 ` Alexander Graf
2020-10-09 11:46 ` [PATCH v2 4/4] selftests: kvm: Test MSR exiting to userspace Aaron Lewis
3 siblings, 1 reply; 8+ messages in thread
From: Aaron Lewis @ 2020-10-09 11:46 UTC (permalink / raw)
To: graf; +Cc: pshier, jmattson, kvm, Aaron Lewis
Add the infrastructure needed to enable exception handling in selftests.
This allows any of the exception and interrupt vectors to be overridden
in the guest.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
v1 -> v2:
- Use exception_handlers instead of gs base to pass table to the guest.
- Move unexpected vector assert to processor.c.
---
tools/testing/selftests/kvm/Makefile | 19 ++-
.../selftests/kvm/include/x86_64/processor.h | 25 ++++
tools/testing/selftests/kvm/lib/kvm_util.c | 5 +
.../selftests/kvm/lib/kvm_util_internal.h | 2 +
.../selftests/kvm/lib/x86_64/handlers.S | 81 +++++++++++++
.../selftests/kvm/lib/x86_64/processor.c | 114 +++++++++++++++++-
6 files changed, 237 insertions(+), 9 deletions(-)
create mode 100644 tools/testing/selftests/kvm/lib/x86_64/handlers.S
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 7ebe71fbca53..aaaf992faf87 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -34,7 +34,7 @@ ifeq ($(ARCH),s390)
endif
LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/sparsebit.c lib/test_util.c
-LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c
+LIBKVM_x86_64 = lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c
LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c
@@ -110,14 +110,21 @@ LDFLAGS += -pthread $(no-pie-option) $(pgste-option)
include ../lib.mk
STATIC_LIBS := $(OUTPUT)/libkvm.a
-LIBKVM_OBJ := $(patsubst %.c, $(OUTPUT)/%.o, $(LIBKVM))
-EXTRA_CLEAN += $(LIBKVM_OBJ) $(STATIC_LIBS) cscope.*
+LIBKVM_C := $(filter %.c,$(LIBKVM))
+LIBKVM_S := $(filter %.S,$(LIBKVM))
+LIBKVM_C_OBJ := $(patsubst %.c, $(OUTPUT)/%.o, $(LIBKVM_C))
+LIBKVM_S_OBJ := $(patsubst %.S, $(OUTPUT)/%.o, $(LIBKVM_S))
+EXTRA_CLEAN += $(LIBKVM_C_OBJ) $(LIBKVM_S_OBJ) $(STATIC_LIBS) cscope.*
+
+x := $(shell mkdir -p $(sort $(dir $(LIBKVM_C_OBJ) $(LIBKVM_S_OBJ))))
+$(LIBKVM_C_OBJ): $(OUTPUT)/%.o: %.c
+ $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
-x := $(shell mkdir -p $(sort $(dir $(LIBKVM_OBJ))))
-$(LIBKVM_OBJ): $(OUTPUT)/%.o: %.c
+$(LIBKVM_S_OBJ): $(OUTPUT)/%.o: %.S
$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
-$(OUTPUT)/libkvm.a: $(LIBKVM_OBJ)
+LIBKVM_OBJS = $(LIBKVM_C_OBJ) $(LIBKVM_S_OBJ)
+$(OUTPUT)/libkvm.a: $(LIBKVM_OBJS)
$(AR) crs $@ $^
x := $(shell mkdir -p $(sort $(dir $(TEST_GEN_PROGS))))
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 0a65e7bb5249..b0a43141fbb3 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -36,6 +36,8 @@
#define X86_CR4_SMAP (1ul << 21)
#define X86_CR4_PKE (1ul << 22)
+#define UNEXPECTED_VECTOR_PORT 0xfff0u
+
/* General Registers in 64-Bit Mode */
struct gpr64_regs {
u64 rax;
@@ -239,6 +241,11 @@ static inline struct desc_ptr get_idt(void)
return idt;
}
+static inline void outl(uint16_t port, uint32_t value)
+{
+ __asm__ __volatile__("outl %%eax, %%dx" : : "d"(port), "a"(value));
+}
+
#define SET_XMM(__var, __xmm) \
asm volatile("movq %0, %%"#__xmm : : "r"(__var) : #__xmm)
@@ -338,6 +345,24 @@ uint32_t kvm_get_cpuid_max_basic(void);
uint32_t kvm_get_cpuid_max_extended(void);
void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits);
+struct ex_regs {
+ uint64_t rax, rcx, rdx, rbx;
+ uint64_t rbp, rsi, rdi;
+ uint64_t r8, r9, r10, r11;
+ uint64_t r12, r13, r14, r15;
+ uint64_t vector;
+ uint64_t error_code;
+ uint64_t rip;
+ uint64_t cs;
+ uint64_t rflags;
+};
+
+void vm_init_descriptor_tables(struct kvm_vm *vm);
+void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid);
+void vm_handle_exception(struct kvm_vm *vm, int vector,
+ void (*handler)(struct ex_regs *));
+void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid);
+
/*
* Basic CPU control in CR0
*/
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 74776ee228f2..ecbb5e4f9ef6 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1195,6 +1195,11 @@ int _vcpu_run(struct kvm_vm *vm, uint32_t vcpuid)
do {
rc = ioctl(vcpu->fd, KVM_RUN, NULL);
} while (rc == -1 && errno == EINTR);
+
+#ifdef __x86_64__
+ assert_on_unhandled_exception(vm, vcpuid);
+#endif
+
return rc;
}
diff --git a/tools/testing/selftests/kvm/lib/kvm_util_internal.h b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
index 2ef446520748..f07d383d03a1 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util_internal.h
+++ b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
@@ -50,6 +50,8 @@ struct kvm_vm {
vm_paddr_t pgd;
vm_vaddr_t gdt;
vm_vaddr_t tss;
+ vm_vaddr_t idt;
+ vm_vaddr_t handlers;
};
struct vcpu *vcpu_find(struct kvm_vm *vm, uint32_t vcpuid);
diff --git a/tools/testing/selftests/kvm/lib/x86_64/handlers.S b/tools/testing/selftests/kvm/lib/x86_64/handlers.S
new file mode 100644
index 000000000000..aaf7bc7d2ce1
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/handlers.S
@@ -0,0 +1,81 @@
+handle_exception:
+ push %r15
+ push %r14
+ push %r13
+ push %r12
+ push %r11
+ push %r10
+ push %r9
+ push %r8
+
+ push %rdi
+ push %rsi
+ push %rbp
+ push %rbx
+ push %rdx
+ push %rcx
+ push %rax
+ mov %rsp, %rdi
+
+ call route_exception
+
+ pop %rax
+ pop %rcx
+ pop %rdx
+ pop %rbx
+ pop %rbp
+ pop %rsi
+ pop %rdi
+ pop %r8
+ pop %r9
+ pop %r10
+ pop %r11
+ pop %r12
+ pop %r13
+ pop %r14
+ pop %r15
+
+ /* Discard vector and error code. */
+ add $16, %rsp
+ iretq
+
+/*
+ * Build the handle_exception wrappers which push the vector/error code on the
+ * stack and an array of pointers to those wrappers.
+ */
+.pushsection .rodata
+.globl idt_handlers
+idt_handlers:
+.popsection
+
+.macro HANDLERS has_error from to
+ vector = \from
+ .rept \to - \from + 1
+ .align 8
+
+ /* Fetch current address and append it to idt_handlers. */
+ current_handler = .
+.pushsection .rodata
+.quad current_handler
+.popsection
+
+ .if ! \has_error
+ pushq $0
+ .endif
+ pushq $vector
+ jmp handle_exception
+ vector = vector + 1
+ .endr
+.endm
+
+.global idt_handler_code
+idt_handler_code:
+ HANDLERS has_error=0 from=0 to=7
+ HANDLERS has_error=1 from=8 to=8
+ HANDLERS has_error=0 from=9 to=9
+ HANDLERS has_error=1 from=10 to=14
+ HANDLERS has_error=0 from=15 to=16
+ HANDLERS has_error=1 from=17 to=17
+ HANDLERS has_error=0 from=18 to=255
+
+.section .note.GNU-stack, "", %progbits
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 1ccf6c9b3476..e642057ecf8a 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -12,9 +12,18 @@
#include "../kvm_util_internal.h"
#include "processor.h"
+#ifndef NUM_INTERRUPTS
+#define NUM_INTERRUPTS 256
+#endif
+
+#define DEFAULT_CODE_SELECTOR 0x8
+#define DEFAULT_DATA_SELECTOR 0x10
+
/* Minimum physical address used for virtual translation tables. */
#define KVM_GUEST_PAGE_TABLE_MIN_PADDR 0x180000
+vm_vaddr_t exception_handlers;
+
/* Virtual translation table structure declarations */
struct pageMapL4Entry {
uint64_t present:1;
@@ -557,9 +566,9 @@ static void vcpu_setup(struct kvm_vm *vm, int vcpuid, int pgd_memslot, int gdt_m
sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
kvm_seg_set_unusable(&sregs.ldt);
- kvm_seg_set_kernel_code_64bit(vm, 0x8, &sregs.cs);
- kvm_seg_set_kernel_data_64bit(vm, 0x10, &sregs.ds);
- kvm_seg_set_kernel_data_64bit(vm, 0x10, &sregs.es);
+ kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs.cs);
+ kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.ds);
+ kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.es);
kvm_setup_tss_64bit(vm, &sregs.tr, 0x18, gdt_memslot, pgd_memslot);
break;
@@ -1119,3 +1128,102 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
*va_bits = (entry->eax >> 8) & 0xff;
}
}
+
+struct idt_entry {
+ uint16_t offset0;
+ uint16_t selector;
+ uint16_t ist : 3;
+ uint16_t : 5;
+ uint16_t type : 4;
+ uint16_t : 1;
+ uint16_t dpl : 2;
+ uint16_t p : 1;
+ uint16_t offset1;
+ uint32_t offset2; uint32_t reserved;
+};
+
+static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
+ int dpl, unsigned short selector)
+{
+ struct idt_entry *base =
+ (struct idt_entry *)addr_gva2hva(vm, vm->idt);
+ struct idt_entry *e = &base[vector];
+
+ memset(e, 0, sizeof(*e));
+ e->offset0 = addr;
+ e->selector = selector;
+ e->ist = 0;
+ e->type = 14;
+ e->dpl = dpl;
+ e->p = 1;
+ e->offset1 = addr >> 16;
+ e->offset2 = addr >> 32;
+}
+
+void kvm_exit_unexpected_vector(uint32_t value)
+{
+ outl(UNEXPECTED_VECTOR_PORT, value);
+}
+
+void route_exception(struct ex_regs *regs)
+{
+ typedef void(*handler)(struct ex_regs *);
+ handler *handlers = (handler *)exception_handlers;
+
+ if (handlers && handlers[regs->vector]) {
+ handlers[regs->vector](regs);
+ return;
+ }
+
+ kvm_exit_unexpected_vector(regs->vector);
+}
+
+void vm_init_descriptor_tables(struct kvm_vm *vm)
+{
+ extern void *idt_handlers;
+ int i;
+
+ vm->idt = vm_vaddr_alloc(vm, getpagesize(), 0x2000, 0, 0);
+ vm->handlers = vm_vaddr_alloc(vm, 256 * sizeof(void *), 0x2000, 0, 0);
+ /* Handlers have the same address in both address spaces.*/
+ for (i = 0; i < NUM_INTERRUPTS; i++)
+ set_idt_entry(vm, i, (unsigned long)(&idt_handlers)[i], 0,
+ DEFAULT_CODE_SELECTOR);
+}
+
+void vcpu_init_descriptor_tables(struct kvm_vm *vm, uint32_t vcpuid)
+{
+ struct kvm_sregs sregs;
+
+ vcpu_sregs_get(vm, vcpuid, &sregs);
+ sregs.idt.base = vm->idt;
+ sregs.idt.limit = NUM_INTERRUPTS * sizeof(struct idt_entry) - 1;
+ sregs.gdt.base = vm->gdt;
+ sregs.gdt.limit = getpagesize() - 1;
+ kvm_seg_set_kernel_data_64bit(NULL, DEFAULT_DATA_SELECTOR, &sregs.gs);
+ vcpu_sregs_set(vm, vcpuid, &sregs);
+ *(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
+}
+
+void vm_handle_exception(struct kvm_vm *vm, int vector,
+ void (*handler)(struct ex_regs *))
+{
+ vm_vaddr_t *handlers = (vm_vaddr_t *)addr_gva2hva(vm, vm->handlers);
+
+ handlers[vector] = (vm_vaddr_t)handler;
+}
+
+void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid)
+{
+ if (vcpu_state(vm, vcpuid)->exit_reason == KVM_EXIT_IO
+ && vcpu_state(vm, vcpuid)->io.port == UNEXPECTED_VECTOR_PORT
+ && vcpu_state(vm, vcpuid)->io.size == 4) {
+ /* Grab pointer to io data */
+ uint32_t *data = (void *)vcpu_state(vm, vcpuid)
+ + vcpu_state(vm, vcpuid)->io.data_offset;
+
+ TEST_ASSERT(false,
+ "Unexpected vectored event in guest (vector:0x%x)",
+ *data);
+ }
+}
\ No newline at end of file
--
2.28.0.1011.ga647a8990f-goog
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v2 4/4] selftests: kvm: Test MSR exiting to userspace
2020-10-09 11:46 [PATCH v2 0/4] Test MSR exits to userspace Aaron Lewis
` (2 preceding siblings ...)
2020-10-09 11:46 ` [PATCH v2 3/4] selftests: kvm: Add exception handling to selftests Aaron Lewis
@ 2020-10-09 11:46 ` Aaron Lewis
3 siblings, 0 replies; 8+ messages in thread
From: Aaron Lewis @ 2020-10-09 11:46 UTC (permalink / raw)
To: graf; +Cc: pshier, jmattson, kvm, Aaron Lewis
Add a selftest to test that when the ioctl KVM_X86_SET_MSR_FILTER is
called with an MSR list, those MSRs exit to userspace.
This test uses 3 MSRs to test this:
1. MSR_IA32_XSS, an MSR the kernel knows about.
2. MSR_IA32_FLUSH_CMD, an MSR the kernel does not know about.
3. MSR_NON_EXISTENT, an MSR invented in this test for the purposes of
passing a fake MSR from the guest to userspace. KVM just acts as a
pass through.
Userspace is also able to inject a #GP. This is demonstrated when
MSR_IA32_XSS and MSR_IA32_FLUSH_CMD are misused in the test. When this
happens a #GP is initiated in userspace to be thrown in the guest which is
handled gracefully by the exception handling framework introduced earlier
in this series.
Tests for the generic instruction emulator were also added. For this to
work the module parameter kvm.force_emulation_prefix=1 has to be enabled.
If it isn't enabled the tests will be skipped.
A test was also added to ensure the MSR permission bitmap is being set
correctly by executing reads and writes of MSR_FS_BASE and MSR_GS_BASE
in the guest while alternating which MSR userspace should intercept. If
the permission bitmap is being set correctly only one of the MSRs should
be coming through at a time, and the guest should be able to read and
write the other one directly.
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
tools/testing/selftests/kvm/lib/kvm_util.c | 2 +
.../kvm/x86_64/userspace_msr_exit_test.c | 560 ++++++++++++++++++
4 files changed, 564 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 307ceaadbbb9..30686fbb8b9f 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -15,6 +15,7 @@
/x86_64/vmx_preemption_timer_test
/x86_64/svm_vmcall_test
/x86_64/sync_regs_test
+/x86_64/userspace_msr_exit_test
/x86_64/vmx_close_while_nested_test
/x86_64/vmx_dirty_log_test
/x86_64/vmx_set_nested_state_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index aaaf992faf87..7acc14d06ba8 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -49,6 +49,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test
TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
+TEST_GEN_PROGS_x86_64 += x86_64/userspace_msr_exit_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index ecbb5e4f9ef6..d5a97401e525 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1595,6 +1595,8 @@ static struct exit_reason {
{KVM_EXIT_INTERNAL_ERROR, "INTERNAL_ERROR"},
{KVM_EXIT_OSI, "OSI"},
{KVM_EXIT_PAPR_HCALL, "PAPR_HCALL"},
+ {KVM_EXIT_X86_RDMSR, "RDMSR"},
+ {KVM_EXIT_X86_WRMSR, "WRMSR"},
#ifdef KVM_EXIT_MEMORY_NOT_PRESENT
{KVM_EXIT_MEMORY_NOT_PRESENT, "MEMORY_NOT_PRESENT"},
#endif
diff --git a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
new file mode 100644
index 000000000000..e8b6918cdea0
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
@@ -0,0 +1,560 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020, Google LLC.
+ *
+ * Tests for exiting into userspace on registered MSRs
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "vmx.h"
+
+/* Forced emulation prefix, used to invoke the emulator unconditionally. */
+#define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
+#define KVM_FEP_LENGTH 5
+static int fep_available = 1;
+
+#define VCPU_ID 1
+#define MSR_NON_EXISTENT 0x474f4f00
+
+u64 deny_bits = 0;
+struct kvm_msr_filter filter = {
+ .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
+ .ranges = {
+ {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ /* Test an MSR the kernel knows about. */
+ .base = MSR_IA32_XSS,
+ .bitmap = (uint8_t*)&deny_bits,
+ }, {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ /* Test an MSR the kernel doesn't know about. */
+ .base = MSR_IA32_FLUSH_CMD,
+ .bitmap = (uint8_t*)&deny_bits,
+ }, {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ /* Test a fabricated MSR that no one knows about. */
+ .base = MSR_NON_EXISTENT,
+ .bitmap = (uint8_t*)&deny_bits,
+ },
+ },
+};
+
+struct kvm_msr_filter filter_fs = {
+ .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
+ .ranges = {
+ {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ .base = MSR_FS_BASE,
+ .bitmap = (uint8_t*)&deny_bits,
+ },
+ },
+};
+
+struct kvm_msr_filter filter_gs = {
+ .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
+ .ranges = {
+ {
+ .flags = KVM_MSR_FILTER_READ |
+ KVM_MSR_FILTER_WRITE,
+ .nmsrs = 1,
+ .base = MSR_GS_BASE,
+ .bitmap = (uint8_t*)&deny_bits,
+ },
+ },
+};
+
+uint64_t msr_non_existent_data;
+int guest_exception_count;
+
+/*
+ * Note: Force test_rdmsr() to not be inlined to prevent the labels,
+ * rdmsr_start and rdmsr_end, from being defined multiple times.
+ */
+static noinline uint64_t test_rdmsr(uint32_t msr)
+{
+ uint32_t a, d;
+
+ guest_exception_count = 0;
+
+ __asm__ __volatile__("rdmsr_start: rdmsr; rdmsr_end:" :
+ "=a"(a), "=d"(d) : "c"(msr) : "memory");
+
+ return a | ((uint64_t) d << 32);
+}
+
+/*
+ * Note: Force test_wrmsr() to not be inlined to prevent the labels,
+ * wrmsr_start and wrmsr_end, from being defined multiple times.
+ */
+static noinline void test_wrmsr(uint32_t msr, uint64_t value)
+{
+ uint32_t a = value;
+ uint32_t d = value >> 32;
+
+ guest_exception_count = 0;
+
+ __asm__ __volatile__("wrmsr_start: wrmsr; wrmsr_end:" ::
+ "a"(a), "d"(d), "c"(msr) : "memory");
+}
+
+extern char rdmsr_start, rdmsr_end;
+extern char wrmsr_start, wrmsr_end;
+
+/*
+ * Note: Force test_em_rdmsr() to not be inlined to prevent the labels,
+ * rdmsr_start and rdmsr_end, from being defined multiple times.
+ */
+static noinline uint64_t test_em_rdmsr(uint32_t msr)
+{
+ uint32_t a, d;
+
+ guest_exception_count = 0;
+
+ __asm__ __volatile__(KVM_FEP "em_rdmsr_start: rdmsr; em_rdmsr_end:" :
+ "=a"(a), "=d"(d) : "c"(msr) : "memory");
+
+ return a | ((uint64_t) d << 32);
+}
+
+/*
+ * Note: Force test_em_wrmsr() to not be inlined to prevent the labels,
+ * wrmsr_start and wrmsr_end, from being defined multiple times.
+ */
+static noinline void test_em_wrmsr(uint32_t msr, uint64_t value)
+{
+ uint32_t a = value;
+ uint32_t d = value >> 32;
+
+ guest_exception_count = 0;
+
+ __asm__ __volatile__(KVM_FEP "em_wrmsr_start: wrmsr; em_wrmsr_end:" ::
+ "a"(a), "d"(d), "c"(msr) : "memory");
+}
+
+extern char em_rdmsr_start, em_rdmsr_end;
+extern char em_wrmsr_start, em_wrmsr_end;
+
+static void guest_code(void)
+{
+ uint64_t data;
+
+ /*
+ * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_XSS.
+ *
+ * A GP is thrown if anything other than 0 is written to
+ * MSR_IA32_XSS.
+ */
+ data = test_rdmsr(MSR_IA32_XSS);
+ GUEST_ASSERT(data == 0);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ test_wrmsr(MSR_IA32_XSS, 0);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ test_wrmsr(MSR_IA32_XSS, 1);
+ GUEST_ASSERT(guest_exception_count == 1);
+
+ /*
+ * Test userspace intercepting rdmsr / wrmsr for MSR_IA32_FLUSH_CMD.
+ *
+ * A GP is thrown if MSR_IA32_FLUSH_CMD is read
+ * from or if a value other than 1 is written to it.
+ */
+ test_rdmsr(MSR_IA32_FLUSH_CMD);
+ GUEST_ASSERT(guest_exception_count == 1);
+
+ test_wrmsr(MSR_IA32_FLUSH_CMD, 0);
+ GUEST_ASSERT(guest_exception_count == 1);
+
+ test_wrmsr(MSR_IA32_FLUSH_CMD, 1);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ /*
+ * Test userspace intercepting rdmsr / wrmsr for MSR_NON_EXISTENT.
+ *
+ * Test that a fabricated MSR can pass through the kernel
+ * and be handled in userspace.
+ */
+ test_wrmsr(MSR_NON_EXISTENT, 2);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ data = test_rdmsr(MSR_NON_EXISTENT);
+ GUEST_ASSERT(data == 2);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ /*
+ * Test to see if the instruction emulator is available (ie: the module
+ * parameter 'kvm.force_emulation_prefix=1' is set). This instruction
+ * will #UD if it isn't available.
+ */
+ __asm__ __volatile__(KVM_FEP "nop");
+
+ if (fep_available) {
+ /* Let userspace know we aren't done. */
+ GUEST_SYNC(0);
+
+ /*
+ * Now run the same tests with the instruction emulator.
+ */
+ data = test_em_rdmsr(MSR_IA32_XSS);
+ GUEST_ASSERT(data == 0);
+ GUEST_ASSERT(guest_exception_count == 0);
+ test_em_wrmsr(MSR_IA32_XSS, 0);
+ GUEST_ASSERT(guest_exception_count == 0);
+ test_em_wrmsr(MSR_IA32_XSS, 1);
+ GUEST_ASSERT(guest_exception_count == 1);
+
+ test_em_rdmsr(MSR_IA32_FLUSH_CMD);
+ GUEST_ASSERT(guest_exception_count == 1);
+ test_em_wrmsr(MSR_IA32_FLUSH_CMD, 0);
+ GUEST_ASSERT(guest_exception_count == 1);
+ test_em_wrmsr(MSR_IA32_FLUSH_CMD, 1);
+ GUEST_ASSERT(guest_exception_count == 0);
+
+ test_em_wrmsr(MSR_NON_EXISTENT, 2);
+ GUEST_ASSERT(guest_exception_count == 0);
+ data = test_em_rdmsr(MSR_NON_EXISTENT);
+ GUEST_ASSERT(data == 2);
+ GUEST_ASSERT(guest_exception_count == 0);
+ }
+
+ GUEST_DONE();
+}
+
+
+static void guest_code_permission_bitmap(void)
+{
+ uint64_t data;
+
+ test_wrmsr(MSR_FS_BASE, 0);
+ data = test_rdmsr(MSR_FS_BASE);
+ GUEST_ASSERT(data == MSR_FS_BASE);
+
+ test_wrmsr(MSR_GS_BASE, 0);
+ data = test_rdmsr(MSR_GS_BASE);
+ GUEST_ASSERT(data == 0);
+
+ /* Let userspace know to switch the filter */
+ GUEST_SYNC(0);
+
+ test_wrmsr(MSR_FS_BASE, 0);
+ data = test_rdmsr(MSR_FS_BASE);
+ GUEST_ASSERT(data == 0);
+
+ test_wrmsr(MSR_GS_BASE, 0);
+ data = test_rdmsr(MSR_GS_BASE);
+ GUEST_ASSERT(data == MSR_GS_BASE);
+
+ GUEST_DONE();
+}
+
+static void __guest_gp_handler(struct ex_regs *regs,
+ char *r_start, char *r_end,
+ char *w_start, char *w_end)
+{
+ if (regs->rip == (uintptr_t)r_start) {
+ regs->rip = (uintptr_t)r_end;
+ regs->rax = 0;
+ regs->rdx = 0;
+ } else if (regs->rip == (uintptr_t)w_start) {
+ regs->rip = (uintptr_t)w_end;
+ } else {
+ GUEST_ASSERT(!"RIP is at an unknown location!");
+ }
+
+ ++guest_exception_count;
+}
+
+static void guest_gp_handler(struct ex_regs *regs)
+{
+ __guest_gp_handler(regs, &rdmsr_start, &rdmsr_end,
+ &wrmsr_start, &wrmsr_end);
+}
+
+static void guest_fep_gp_handler(struct ex_regs *regs)
+{
+ __guest_gp_handler(regs, &em_rdmsr_start, &em_rdmsr_end,
+ &em_wrmsr_start, &em_wrmsr_end);
+}
+
+static void guest_ud_handler(struct ex_regs *regs)
+{
+ fep_available = 0;
+ regs->rip += KVM_FEP_LENGTH;
+}
+
+static void run_guest(struct kvm_vm *vm)
+{
+ int rc;
+
+ rc = _vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc);
+}
+
+static void check_for_guest_assert(struct kvm_vm *vm)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+ struct ucall uc;
+
+ if (run->exit_reason == KVM_EXIT_IO &&
+ get_ucall(vm, VCPU_ID, &uc) == UCALL_ABORT) {
+ TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
+ __FILE__, uc.args[1]);
+ }
+}
+
+static void process_rdmsr(struct kvm_vm *vm, uint32_t msr_index)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+
+ check_for_guest_assert(vm);
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_RDMSR,
+ "Unexpected exit reason: %u (%s),\n",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+ TEST_ASSERT(run->msr.index == msr_index,
+ "Unexpected msr (0x%04x), expected 0x%04x",
+ run->msr.index, msr_index);
+
+ switch (run->msr.index) {
+ case MSR_IA32_XSS:
+ run->msr.data = 0;
+ break;
+ case MSR_IA32_FLUSH_CMD:
+ run->msr.error = 1;
+ break;
+ case MSR_NON_EXISTENT:
+ run->msr.data = msr_non_existent_data;
+ break;
+ case MSR_FS_BASE:
+ run->msr.data = MSR_FS_BASE;
+ break;
+ case MSR_GS_BASE:
+ run->msr.data = MSR_GS_BASE;
+ break;
+ default:
+ TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
+ }
+}
+
+static void process_wrmsr(struct kvm_vm *vm, uint32_t msr_index)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+
+ check_for_guest_assert(vm);
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_X86_WRMSR,
+ "Unexpected exit reason: %u (%s),\n",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+ TEST_ASSERT(run->msr.index == msr_index,
+ "Unexpected msr (0x%04x), expected 0x%04x",
+ run->msr.index, msr_index);
+
+ switch (run->msr.index) {
+ case MSR_IA32_XSS:
+ if (run->msr.data != 0)
+ run->msr.error = 1;
+ break;
+ case MSR_IA32_FLUSH_CMD:
+ if (run->msr.data != 1)
+ run->msr.error = 1;
+ break;
+ case MSR_NON_EXISTENT:
+ msr_non_existent_data = run->msr.data;
+ break;
+ case MSR_FS_BASE:
+ case MSR_GS_BASE:
+ break;
+ default:
+ TEST_ASSERT(false, "Unexpected MSR: 0x%04x", run->msr.index);
+ }
+}
+
+static void process_ucall_done(struct kvm_vm *vm)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+ struct ucall uc;
+
+ check_for_guest_assert(vm);
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Unexpected exit reason: %u (%s)",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ TEST_ASSERT(get_ucall(vm, VCPU_ID, &uc) == UCALL_DONE,
+ "Unexpected ucall command: %lu, expected UCALL_DONE (%d)",
+ uc.cmd, UCALL_DONE);
+}
+
+static uint64_t process_ucall(struct kvm_vm *vm)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+ struct ucall uc = {};
+
+ check_for_guest_assert(vm);
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Unexpected exit reason: %u (%s)",
+ run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ switch (get_ucall(vm, VCPU_ID, &uc)) {
+ case UCALL_SYNC:
+ break;
+ case UCALL_ABORT:
+ check_for_guest_assert(vm);
+ break;
+ case UCALL_DONE:
+ process_ucall_done(vm);
+ break;
+ default:
+ TEST_ASSERT(false, "Unexpected ucall");
+ }
+
+ return uc.cmd;
+}
+
+static void run_guest_then_process_rdmsr(struct kvm_vm *vm, uint32_t msr_index)
+{
+ run_guest(vm);
+ process_rdmsr(vm, msr_index);
+}
+
+static void run_guest_then_process_wrmsr(struct kvm_vm *vm, uint32_t msr_index)
+{
+ run_guest(vm);
+ process_wrmsr(vm, msr_index);
+}
+
+static uint64_t run_guest_then_process_ucall(struct kvm_vm *vm)
+{
+ run_guest(vm);
+ return process_ucall(vm);
+}
+
+static void run_guest_then_process_ucall_done(struct kvm_vm *vm)
+{
+ run_guest(vm);
+ process_ucall_done(vm);
+}
+
+static void test_msr_filter(void) {
+ struct kvm_enable_cap cap = {
+ .cap = KVM_CAP_X86_USER_SPACE_MSR,
+ .args[0] = KVM_MSR_EXIT_REASON_FILTER,
+ };
+ struct kvm_vm *vm;
+ int rc;
+
+ /* Create VM */
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+
+ rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
+ TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
+ vm_enable_cap(vm, &cap);
+
+ rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
+ TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");
+
+ vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter);
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+
+ vm_handle_exception(vm, GP_VECTOR, guest_gp_handler);
+
+ /* Process guest code userspace exits. */
+ run_guest_then_process_rdmsr(vm, MSR_IA32_XSS);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
+
+ run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
+
+ run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT);
+ run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT);
+
+ vm_handle_exception(vm, UD_VECTOR, guest_ud_handler);
+ run_guest(vm);
+ vm_handle_exception(vm, UD_VECTOR, NULL);
+
+ if (process_ucall(vm) != UCALL_DONE) {
+ vm_handle_exception(vm, GP_VECTOR, guest_fep_gp_handler);
+
+ /* Process emulated rdmsr and wrmsr instructions. */
+ run_guest_then_process_rdmsr(vm, MSR_IA32_XSS);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_XSS);
+
+ run_guest_then_process_rdmsr(vm, MSR_IA32_FLUSH_CMD);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
+ run_guest_then_process_wrmsr(vm, MSR_IA32_FLUSH_CMD);
+
+ run_guest_then_process_wrmsr(vm, MSR_NON_EXISTENT);
+ run_guest_then_process_rdmsr(vm, MSR_NON_EXISTENT);
+
+ /* Confirm the guest completed without issues. */
+ run_guest_then_process_ucall_done(vm);
+ } else {
+ printf("To run the instruction emulated tests set the module parameter 'kvm.force_emulation_prefix=1'\n");
+ }
+
+ kvm_vm_free(vm);
+}
+
+static void test_msr_permission_bitmap(void) {
+ struct kvm_enable_cap cap = {
+ .cap = KVM_CAP_X86_USER_SPACE_MSR,
+ .args[0] = KVM_MSR_EXIT_REASON_FILTER,
+ };
+ struct kvm_vm *vm;
+ int rc;
+
+ /* Create VM */
+ vm = vm_create_default(VCPU_ID, 0, guest_code_permission_bitmap);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+
+ rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
+ TEST_ASSERT(rc, "KVM_CAP_X86_USER_SPACE_MSR is available");
+ vm_enable_cap(vm, &cap);
+
+ rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
+ TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");
+
+ vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_fs);
+ run_guest_then_process_wrmsr(vm, MSR_FS_BASE);
+ run_guest_then_process_rdmsr(vm, MSR_FS_BASE);
+ TEST_ASSERT(run_guest_then_process_ucall(vm) == UCALL_SYNC, "Expected ucall state to be UCALL_SYNC.");
+ vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_gs);
+ run_guest_then_process_wrmsr(vm, MSR_GS_BASE);
+ run_guest_then_process_rdmsr(vm, MSR_GS_BASE);
+ run_guest_then_process_ucall_done(vm);
+
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ test_msr_filter();
+
+ test_msr_permission_bitmap();
+
+ return 0;
+}
--
2.28.0.1011.ga647a8990f-goog
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