[PATCH 4/5] KVM: selftests: Use exception fixup for #UD/#GP Hyper-V MSR/hcall tests

Sean Christopherson
2022-06-08T22:45:34Z

Use exception fixup to verify VMCALL/RDMSR/WRMSR fault as expected in the
Hyper-V Features test.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
.../selftests/kvm/x86_64/hyperv_features.c | 117 +++++-------------
1 file changed, 33 insertions(+), 84 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_features.c b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
index 5ec40422d72a..0de13ab38e8b 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_features.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
@@ -15,75 +15,20 @@

#define LINUX_OS_ID ((u64)0x8100 << 48)

-extern unsigned char rdmsr_start;
-extern unsigned char rdmsr_end;
-
-static u64 do_rdmsr(u32 idx)
-{
- u32 lo, hi;
-
- asm volatile("rdmsr_start: rdmsr;"
- "rdmsr_end:"
- : "=a"(lo), "=c"(hi)
- : "c"(idx));
-
- return (((u64) hi) << 32) | lo;
-}
-
-extern unsigned char wrmsr_start;
-extern unsigned char wrmsr_end;
-
-static void do_wrmsr(u32 idx, u64 val)
-{
- u32 lo, hi;
-
- lo = val;
- hi = val >> 32;
-
- asm volatile("wrmsr_start: wrmsr;"
- "wrmsr_end:"
- : : "a"(lo), "c"(idx), "d"(hi));
-}
-
-static int nr_gp;
-static int nr_ud;
-
-static inline u64 hypercall(u64 control, vm_vaddr_t input_address,
- vm_vaddr_t output_address)
-{
- u64 hv_status;
-
- asm volatile("mov %3, %%r8\n"
- "vmcall"
- : "=a" (hv_status),
- "+c" (control), "+d" (input_address)
- : "r" (output_address)
- : "cc", "memory", "r8", "r9", "r10", "r11");
-
- return hv_status;
-}
-
-static void guest_gp_handler(struct ex_regs *regs)
-{
- unsigned char *rip = (unsigned char *)regs->rip;
- bool r, w;
-
- r = rip == &rdmsr_start;
- w = rip == &wrmsr_start;
- GUEST_ASSERT(r || w);
-
- nr_gp++;
-
- if (r)
- regs->rip = (uint64_t)&rdmsr_end;
- else
- regs->rip = (uint64_t)&wrmsr_end;
-}
-
-static void guest_ud_handler(struct ex_regs *regs)
-{
- nr_ud++;
- regs->rip += 3;
+static inline uint8_t hypercall(u64 control, vm_vaddr_t input_address,
+ vm_vaddr_t output_address, uint64_t *hv_status)
+{
+ uint8_t vector;
+
+ /* Note both the hypercall and the "asm safe" clobber r9-r11. */
+ asm volatile("mov %[output_address], %%r8\n\t"
+ KVM_ASM_SAFE("vmcall")
+ : "=a" (*hv_status),
+ "+c" (control), "+d" (input_address),
+ KVM_ASM_SAFE_OUTPUTS(vector)
+ : [output_address] "r"(output_address)
+ : "cc", "memory", "r8", KVM_ASM_SAFE_CLOBBERS);
+ return vector;
}

struct msr_data {
@@ -101,31 +46,33 @@ struct hcall_data {

static void guest_msr(struct msr_data *msr)
{
+ uint64_t ignored;
+ uint8_t vector;
+
GUEST_ASSERT(msr->idx);

- WRITE_ONCE(nr_gp, 0);
if (!msr->write)
- do_rdmsr(msr->idx);
+ vector = rdmsr_safe(msr->idx, &ignored);
else
- do_wrmsr(msr->idx, msr->write_val);
+ vector = wrmsr_safe(msr->idx, msr->write_val);

if (msr->available)
- GUEST_ASSERT(READ_ONCE(nr_gp) == 0);
+ GUEST_ASSERT_2(!vector, msr->idx, vector);
else
- GUEST_ASSERT(READ_ONCE(nr_gp) == 1);
+ GUEST_ASSERT_2(vector == GP_VECTOR, msr->idx, vector);
GUEST_DONE();
}

static void guest_hcall(vm_vaddr_t pgs_gpa, struct hcall_data *hcall)
{
u64 res, input, output;
+ uint8_t vector;

GUEST_ASSERT(hcall->control);

wrmsr(HV_X64_MSR_GUEST_OS_ID, LINUX_OS_ID);
wrmsr(HV_X64_MSR_HYPERCALL, pgs_gpa);

- nr_ud = 0;
if (!(hcall->control & HV_HYPERCALL_FAST_BIT)) {
input = pgs_gpa;
output = pgs_gpa + 4096;
@@ -133,12 +80,14 @@ static void guest_hcall(vm_vaddr_t pgs_gpa, struct hcall_data *hcall)
input = output = 0;
}

- res = hypercall(hcall->control, input, output);
+ vector = hypercall(hcall->control, input, output, &res);
if (hcall->ud_expected)
- GUEST_ASSERT(nr_ud == 1);
+ GUEST_ASSERT_2(vector == UD_VECTOR, hcall->control, vector);
else
- GUEST_ASSERT(res == hcall->expect);
+ GUEST_ASSERT_2(!vector, hcall->control, vector);

+ GUEST_ASSERT_2(!hcall->ud_expected || res == hcall->expect,
+ hcall->expect, res);
GUEST_DONE();
}

@@ -190,7 +139,6 @@ static void guest_test_msrs_access(void)

vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vcpu);
- vm_install_exception_handler(vm, GP_VECTOR, guest_gp_handler);

run = vcpu->run;

@@ -499,8 +447,9 @@ static void guest_test_msrs_access(void)

switch (get_ucall(vcpu, &uc)) {
case UCALL_ABORT:
- TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
- __FILE__, uc.args[1]);
+ TEST_FAIL("%s at %s:%ld, MSR = %lx, vector = %lx",
+ (const char *)uc.args[0], __FILE__,
+ uc.args[1], uc.args[2], uc.args[3]);
return;
case UCALL_DONE:
break;
@@ -531,7 +480,6 @@ static void guest_test_hcalls_access(void)

vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(vcpu);
- vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler);

/* Hypercall input/output */
hcall_page = vm_vaddr_alloc_pages(vm, 2);
@@ -672,8 +620,9 @@ static void guest_test_hcalls_access(void)

switch (get_ucall(vcpu, &uc)) {
case UCALL_ABORT:
- TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
- __FILE__, uc.args[1]);
+ TEST_FAIL("%s at %s:%ld, arg1 = %lx, arg2 = %lx",
+ (const char *)uc.args[0], __FILE__,
+ uc.args[1], uc.args[2], uc.args[3]);
return;
case UCALL_DONE:
break;
--
2.36.1.255.ge46751e96f-goog