selftests: kvm: Merge user_msr_test into userspace_msr_exit_test

Both user_msr_test and userspace_msr_exit_test tests the functionality
of kvm_msr_filter.  Instead of testing this feature in two tests, merge
them together, so there is only one test for this feature.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Message-Id: <20201204172530.2958493-1-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 236 insertions, 279 deletions

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 5008bf90772b..ce8f4ad39684 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -17,7 +17,6 @@
 /x86_64/svm_vmcall_test
 /x86_64/sync_regs_test
 /x86_64/tsc_msrs_test
-/x86_64/user_msr_test
 /x86_64/userspace_msr_exit_test
 /x86_64/vmx_apic_access_test
 /x86_64/vmx_close_while_nested_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index d54870db21c4..86ccca8ca89d 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -50,7 +50,6 @@ 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/user_msr_test
 TEST_GEN_PROGS_x86_64 += x86_64/userspace_msr_exit_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_apic_access_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
diff --git a/tools/testing/selftests/kvm/x86_64/user_msr_test.c b/tools/testing/selftests/kvm/x86_64/user_msr_test.c
deleted file mode 100644
index fe88b98908ee..000000000000
--- a/tools/testing/selftests/kvm/x86_64/user_msr_test.c
+++ /dev/null
@@ -1,251 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * tests for KVM_CAP_X86_USER_SPACE_MSR and KVM_X86_SET_MSR_FILTER
- *
- * Copyright (C) 2020, Amazon Inc.
- *
- * This is a functional test to verify that we can deflect MSR events
- * into user space.
- */
-#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 "test_util.h"
-
-#include "kvm_util.h"
-#include "processor.h"
-
-#define VCPU_ID                  5
-
-static u32 msr_reads, msr_writes;
-
-static u8 bitmap_00000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
-static u8 bitmap_00000000_write[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
-static u8 bitmap_40000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
-static u8 bitmap_c0000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
-static u8 bitmap_c0000000_read[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
-static u8 bitmap_deadbeef[1] = { 0x1 };
-
-static void deny_msr(uint8_t *bitmap, u32 msr)
-{
-	u32 idx = msr & (KVM_MSR_FILTER_MAX_BITMAP_SIZE - 1);
-
-	bitmap[idx / 8] &= ~(1 << (idx % 8));
-}
-
-static void prepare_bitmaps(void)
-{
-	memset(bitmap_00000000, 0xff, sizeof(bitmap_00000000));
-	memset(bitmap_00000000_write, 0xff, sizeof(bitmap_00000000_write));
-	memset(bitmap_40000000, 0xff, sizeof(bitmap_40000000));
-	memset(bitmap_c0000000, 0xff, sizeof(bitmap_c0000000));
-	memset(bitmap_c0000000_read, 0xff, sizeof(bitmap_c0000000_read));
-
-	deny_msr(bitmap_00000000_write, MSR_IA32_POWER_CTL);
-	deny_msr(bitmap_c0000000_read, MSR_SYSCALL_MASK);
-	deny_msr(bitmap_c0000000_read, MSR_GS_BASE);
-}
-
-struct kvm_msr_filter filter = {
-	.flags = KVM_MSR_FILTER_DEFAULT_DENY,
-	.ranges = {
-		{
-			.flags = KVM_MSR_FILTER_READ,
-			.base = 0x00000000,
-			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
-			.bitmap = bitmap_00000000,
-		}, {
-			.flags = KVM_MSR_FILTER_WRITE,
-			.base = 0x00000000,
-			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
-			.bitmap = bitmap_00000000_write,
-		}, {
-			.flags = KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE,
-			.base = 0x40000000,
-			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
-			.bitmap = bitmap_40000000,
-		}, {
-			.flags = KVM_MSR_FILTER_READ,
-			.base = 0xc0000000,
-			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
-			.bitmap = bitmap_c0000000_read,
-		}, {
-			.flags = KVM_MSR_FILTER_WRITE,
-			.base = 0xc0000000,
-			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
-			.bitmap = bitmap_c0000000,
-		}, {
-			.flags = KVM_MSR_FILTER_WRITE | KVM_MSR_FILTER_READ,
-			.base = 0xdeadbeef,
-			.nmsrs = 1,
-			.bitmap = bitmap_deadbeef,
-		},
-	},
-};
-
-struct kvm_msr_filter no_filter = {
-	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
-};
-
-static void guest_msr_calls(bool trapped)
-{
-	/* This goes into the in-kernel emulation */
-	wrmsr(MSR_SYSCALL_MASK, 0);
-
-	if (trapped) {
-		/* This goes into user space emulation */
-		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) == MSR_SYSCALL_MASK);
-		GUEST_ASSERT(rdmsr(MSR_GS_BASE) == MSR_GS_BASE);
-	} else {
-		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) != MSR_SYSCALL_MASK);
-		GUEST_ASSERT(rdmsr(MSR_GS_BASE) != MSR_GS_BASE);
-	}
-
-	/* If trapped == true, this goes into user space emulation */
-	wrmsr(MSR_IA32_POWER_CTL, 0x1234);
-
-	/* This goes into the in-kernel emulation */
-	rdmsr(MSR_IA32_POWER_CTL);
-
-	/* Invalid MSR, should always be handled by user space exit */
-	GUEST_ASSERT(rdmsr(0xdeadbeef) == 0xdeadbeef);
-	wrmsr(0xdeadbeef, 0x1234);
-}
-
-static void guest_code(void)
-{
-	guest_msr_calls(true);
-
-	/*
-	 * Disable msr filtering, so that the kernel
-	 * handles everything in the next round
-	 */
-	GUEST_SYNC(0);
-
-	guest_msr_calls(false);
-
-	GUEST_DONE();
-}
-
-static int handle_ucall(struct kvm_vm *vm)
-{
-	struct ucall uc;
-
-	switch (get_ucall(vm, VCPU_ID, &uc)) {
-	case UCALL_ABORT:
-		TEST_FAIL("Guest assertion not met");
-		break;
-	case UCALL_SYNC:
-		vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &no_filter);
-		break;
-	case UCALL_DONE:
-		return 1;
-	default:
-		TEST_FAIL("Unknown ucall %lu", uc.cmd);
-	}
-
-	return 0;
-}
-
-static void handle_rdmsr(struct kvm_run *run)
-{
-	run->msr.data = run->msr.index;
-	msr_reads++;
-
-	if (run->msr.index == MSR_SYSCALL_MASK ||
-	    run->msr.index == MSR_GS_BASE) {
-		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
-			    "MSR read trap w/o access fault");
-	}
-
-	if (run->msr.index == 0xdeadbeef) {
-		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
-			    "MSR deadbeef read trap w/o inval fault");
-	}
-}
-
-static void handle_wrmsr(struct kvm_run *run)
-{
-	/* ignore */
-	msr_writes++;
-
-	if (run->msr.index == MSR_IA32_POWER_CTL) {
-		TEST_ASSERT(run->msr.data == 0x1234,
-			    "MSR data for MSR_IA32_POWER_CTL incorrect");
-		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
-			    "MSR_IA32_POWER_CTL trap w/o access fault");
-	}
-
-	if (run->msr.index == 0xdeadbeef) {
-		TEST_ASSERT(run->msr.data == 0x1234,
-			    "MSR data for deadbeef incorrect");
-		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
-			    "deadbeef trap w/o inval fault");
-	}
-}
-
-int main(int argc, char *argv[])
-{
-	struct kvm_enable_cap cap = {
-		.cap = KVM_CAP_X86_USER_SPACE_MSR,
-		.args[0] = KVM_MSR_EXIT_REASON_INVAL |
-			   KVM_MSR_EXIT_REASON_UNKNOWN |
-			   KVM_MSR_EXIT_REASON_FILTER,
-	};
-	struct kvm_vm *vm;
-	struct kvm_run *run;
-	int rc;
-
-	/* Tell stdout not to buffer its content */
-	setbuf(stdout, NULL);
-
-	/* Create VM */
-	vm = vm_create_default(VCPU_ID, 0, guest_code);
-	run = vcpu_state(vm, VCPU_ID);
-
-	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
-	if (!rc) {
-		print_skip("KVM_CAP_X86_USER_SPACE_MSR not supported");
-		exit(KSFT_SKIP);
-	}
-
-	vm_enable_cap(vm, &cap);
-
-	rc = kvm_check_cap(KVM_CAP_X86_MSR_FILTER);
-	TEST_ASSERT(rc, "KVM_CAP_X86_MSR_FILTER is available");
-
-	prepare_bitmaps();
-	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter);
-
-	while (1) {
-		rc = _vcpu_run(vm, VCPU_ID);
-
-		TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc);
-
-		switch (run->exit_reason) {
-		case KVM_EXIT_X86_RDMSR:
-			handle_rdmsr(run);
-			break;
-		case KVM_EXIT_X86_WRMSR:
-			handle_wrmsr(run);
-			break;
-		case KVM_EXIT_IO:
-			if (handle_ucall(vm))
-				goto done;
-			break;
-		}
-
-	}
-
-done:
-	TEST_ASSERT(msr_reads == 4, "Handled 4 rdmsr in user space");
-	TEST_ASSERT(msr_writes == 3, "Handled 3 wrmsr in user space");
-
-	kvm_vm_free(vm);
-
-	return 0;
-}
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
index e8b6918cdea0..72c0d0797522 100644
--- a/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
+++ b/tools/testing/selftests/kvm/x86_64/userspace_msr_exit_test.c
@@ -20,8 +20,8 @@ static int fep_available = 1;
 #define VCPU_ID	      1
 #define MSR_NON_EXISTENT 0x474f4f00
 
-u64 deny_bits = 0;
-struct kvm_msr_filter filter = {
+static u64 deny_bits = 0;
+struct kvm_msr_filter filter_allow = {
 	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
 	.ranges = {
 		{
@@ -53,8 +53,7 @@ struct kvm_msr_filter filter_fs = {
 	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
 	.ranges = {
 		{
-			.flags = KVM_MSR_FILTER_READ |
-				 KVM_MSR_FILTER_WRITE,
+			.flags = KVM_MSR_FILTER_READ,
 			.nmsrs = 1,
 			.base = MSR_FS_BASE,
 			.bitmap = (uint8_t*)&deny_bits,
@@ -66,8 +65,7 @@ struct kvm_msr_filter filter_gs = {
 	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
 	.ranges = {
 		{
-			.flags = KVM_MSR_FILTER_READ |
-				 KVM_MSR_FILTER_WRITE,
+			.flags = KVM_MSR_FILTER_READ,
 			.nmsrs = 1,
 			.base = MSR_GS_BASE,
 			.bitmap = (uint8_t*)&deny_bits,
@@ -75,8 +73,77 @@ struct kvm_msr_filter filter_gs = {
 	},
 };
 
-uint64_t msr_non_existent_data;
-int guest_exception_count;
+static uint64_t msr_non_existent_data;
+static int guest_exception_count;
+static u32 msr_reads, msr_writes;
+
+static u8 bitmap_00000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
+static u8 bitmap_00000000_write[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
+static u8 bitmap_40000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
+static u8 bitmap_c0000000[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
+static u8 bitmap_c0000000_read[KVM_MSR_FILTER_MAX_BITMAP_SIZE];
+static u8 bitmap_deadbeef[1] = { 0x1 };
+
+static void deny_msr(uint8_t *bitmap, u32 msr)
+{
+	u32 idx = msr & (KVM_MSR_FILTER_MAX_BITMAP_SIZE - 1);
+
+	bitmap[idx / 8] &= ~(1 << (idx % 8));
+}
+
+static void prepare_bitmaps(void)
+{
+	memset(bitmap_00000000, 0xff, sizeof(bitmap_00000000));
+	memset(bitmap_00000000_write, 0xff, sizeof(bitmap_00000000_write));
+	memset(bitmap_40000000, 0xff, sizeof(bitmap_40000000));
+	memset(bitmap_c0000000, 0xff, sizeof(bitmap_c0000000));
+	memset(bitmap_c0000000_read, 0xff, sizeof(bitmap_c0000000_read));
+
+	deny_msr(bitmap_00000000_write, MSR_IA32_POWER_CTL);
+	deny_msr(bitmap_c0000000_read, MSR_SYSCALL_MASK);
+	deny_msr(bitmap_c0000000_read, MSR_GS_BASE);
+}
+
+struct kvm_msr_filter filter_deny = {
+	.flags = KVM_MSR_FILTER_DEFAULT_DENY,
+	.ranges = {
+		{
+			.flags = KVM_MSR_FILTER_READ,
+			.base = 0x00000000,
+			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
+			.bitmap = bitmap_00000000,
+		}, {
+			.flags = KVM_MSR_FILTER_WRITE,
+			.base = 0x00000000,
+			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
+			.bitmap = bitmap_00000000_write,
+		}, {
+			.flags = KVM_MSR_FILTER_READ | KVM_MSR_FILTER_WRITE,
+			.base = 0x40000000,
+			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
+			.bitmap = bitmap_40000000,
+		}, {
+			.flags = KVM_MSR_FILTER_READ,
+			.base = 0xc0000000,
+			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
+			.bitmap = bitmap_c0000000_read,
+		}, {
+			.flags = KVM_MSR_FILTER_WRITE,
+			.base = 0xc0000000,
+			.nmsrs = KVM_MSR_FILTER_MAX_BITMAP_SIZE * BITS_PER_BYTE,
+			.bitmap = bitmap_c0000000,
+		}, {
+			.flags = KVM_MSR_FILTER_WRITE | KVM_MSR_FILTER_READ,
+			.base = 0xdeadbeef,
+			.nmsrs = 1,
+			.bitmap = bitmap_deadbeef,
+		},
+	},
+};
+
+struct kvm_msr_filter no_filter_deny = {
+	.flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
+};
 
 /*
  * Note: Force test_rdmsr() to not be inlined to prevent the labels,
@@ -146,7 +213,7 @@ static noinline void test_em_wrmsr(uint32_t msr, uint64_t value)
 extern char em_rdmsr_start, em_rdmsr_end;
 extern char em_wrmsr_start, em_wrmsr_end;
 
-static void guest_code(void)
+static void guest_code_filter_allow(void)
 {
 	uint64_t data;
 
@@ -233,27 +300,60 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
+static void guest_msr_calls(bool trapped)
+{
+	/* This goes into the in-kernel emulation */
+	wrmsr(MSR_SYSCALL_MASK, 0);
+
+	if (trapped) {
+		/* This goes into user space emulation */
+		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) == MSR_SYSCALL_MASK);
+		GUEST_ASSERT(rdmsr(MSR_GS_BASE) == MSR_GS_BASE);
+	} else {
+		GUEST_ASSERT(rdmsr(MSR_SYSCALL_MASK) != MSR_SYSCALL_MASK);
+		GUEST_ASSERT(rdmsr(MSR_GS_BASE) != MSR_GS_BASE);
+	}
+
+	/* If trapped == true, this goes into user space emulation */
+	wrmsr(MSR_IA32_POWER_CTL, 0x1234);
+
+	/* This goes into the in-kernel emulation */
+	rdmsr(MSR_IA32_POWER_CTL);
+
+	/* Invalid MSR, should always be handled by user space exit */
+	GUEST_ASSERT(rdmsr(0xdeadbeef) == 0xdeadbeef);
+	wrmsr(0xdeadbeef, 0x1234);
+}
+
+static void guest_code_filter_deny(void)
+{
+	guest_msr_calls(true);
+
+	/*
+	 * Disable msr filtering, so that the kernel
+	 * handles everything in the next round
+	 */
+	GUEST_SYNC(0);
+
+	guest_msr_calls(false);
+
+	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);
+	GUEST_ASSERT(data != MSR_GS_BASE);
 
 	/* 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);
+	GUEST_ASSERT(data != MSR_FS_BASE);
 	data = test_rdmsr(MSR_GS_BASE);
 	GUEST_ASSERT(data == MSR_GS_BASE);
 
@@ -376,9 +476,6 @@ static void process_wrmsr(struct kvm_vm *vm, uint32_t msr_index)
 	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);
 	}
@@ -453,7 +550,7 @@ static void run_guest_then_process_ucall_done(struct kvm_vm *vm)
 	process_ucall_done(vm);
 }
 
-static void test_msr_filter(void) {
+static void test_msr_filter_allow(void) {
 	struct kvm_enable_cap cap = {
 		.cap = KVM_CAP_X86_USER_SPACE_MSR,
 		.args[0] = KVM_MSR_EXIT_REASON_FILTER,
@@ -462,7 +559,7 @@ static void test_msr_filter(void) {
 	int rc;
 
 	/* Create VM */
-	vm = vm_create_default(VCPU_ID, 0, guest_code);
+	vm = vm_create_default(VCPU_ID, 0, guest_code_filter_allow);
 	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
 
 	rc = kvm_check_cap(KVM_CAP_X86_USER_SPACE_MSR);
@@ -472,7 +569,7 @@ static void test_msr_filter(void) {
 	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_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_allow);
 
 	vm_init_descriptor_tables(vm);
 	vcpu_init_descriptor_tables(vm, VCPU_ID);
@@ -519,6 +616,116 @@ static void test_msr_filter(void) {
 	kvm_vm_free(vm);
 }
 
+static int handle_ucall(struct kvm_vm *vm)
+{
+	struct ucall uc;
+
+	switch (get_ucall(vm, VCPU_ID, &uc)) {
+	case UCALL_ABORT:
+		TEST_FAIL("Guest assertion not met");
+		break;
+	case UCALL_SYNC:
+		vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &no_filter_deny);
+		break;
+	case UCALL_DONE:
+		return 1;
+	default:
+		TEST_FAIL("Unknown ucall %lu", uc.cmd);
+	}
+
+	return 0;
+}
+
+static void handle_rdmsr(struct kvm_run *run)
+{
+	run->msr.data = run->msr.index;
+	msr_reads++;
+
+	if (run->msr.index == MSR_SYSCALL_MASK ||
+	    run->msr.index == MSR_GS_BASE) {
+		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
+			    "MSR read trap w/o access fault");
+	}
+
+	if (run->msr.index == 0xdeadbeef) {
+		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
+			    "MSR deadbeef read trap w/o inval fault");
+	}
+}
+
+static void handle_wrmsr(struct kvm_run *run)
+{
+	/* ignore */
+	msr_writes++;
+
+	if (run->msr.index == MSR_IA32_POWER_CTL) {
+		TEST_ASSERT(run->msr.data == 0x1234,
+			    "MSR data for MSR_IA32_POWER_CTL incorrect");
+		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_FILTER,
+			    "MSR_IA32_POWER_CTL trap w/o access fault");
+	}
+
+	if (run->msr.index == 0xdeadbeef) {
+		TEST_ASSERT(run->msr.data == 0x1234,
+			    "MSR data for deadbeef incorrect");
+		TEST_ASSERT(run->msr.reason == KVM_MSR_EXIT_REASON_UNKNOWN,
+			    "deadbeef trap w/o inval fault");
+	}
+}
+
+static void test_msr_filter_deny(void) {
+	struct kvm_enable_cap cap = {
+		.cap = KVM_CAP_X86_USER_SPACE_MSR,
+		.args[0] = KVM_MSR_EXIT_REASON_INVAL |
+			   KVM_MSR_EXIT_REASON_UNKNOWN |
+			   KVM_MSR_EXIT_REASON_FILTER,
+	};
+	struct kvm_vm *vm;
+	struct kvm_run *run;
+	int rc;
+
+	/* Create VM */
+	vm = vm_create_default(VCPU_ID, 0, guest_code_filter_deny);
+	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+	run = vcpu_state(vm, VCPU_ID);
+
+	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");
+
+	prepare_bitmaps();
+	vm_ioctl(vm, KVM_X86_SET_MSR_FILTER, &filter_deny);
+
+	while (1) {
+		rc = _vcpu_run(vm, VCPU_ID);
+
+		TEST_ASSERT(rc == 0, "vcpu_run failed: %d\n", rc);
+
+		switch (run->exit_reason) {
+		case KVM_EXIT_X86_RDMSR:
+			handle_rdmsr(run);
+			break;
+		case KVM_EXIT_X86_WRMSR:
+			handle_wrmsr(run);
+			break;
+		case KVM_EXIT_IO:
+			if (handle_ucall(vm))
+				goto done;
+			break;
+		}
+
+	}
+
+done:
+	TEST_ASSERT(msr_reads == 4, "Handled 4 rdmsr in user space");
+	TEST_ASSERT(msr_writes == 3, "Handled 3 wrmsr in user space");
+
+	kvm_vm_free(vm);
+}
+
 static void test_msr_permission_bitmap(void) {
 	struct kvm_enable_cap cap = {
 		.cap = KVM_CAP_X86_USER_SPACE_MSR,
@@ -539,11 +746,9 @@ static void test_msr_permission_bitmap(void) {
 	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);
 
@@ -552,7 +757,12 @@ static void test_msr_permission_bitmap(void) {
 
 int main(int argc, char *argv[])
 {
-	test_msr_filter();
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	test_msr_filter_allow();
+
+	test_msr_filter_deny();
 
 	test_msr_permission_bitmap();