From 55626ca9c6909d077eca71bccbe15fef6e5ad917 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 26 Mar 2021 16:55:51 +0100 Subject: [PATCH] selftests: kvm: Check that TSC page value is small after KVM_SET_CLOCK(0) Add a test for the issue when KVM_SET_CLOCK(0) call could cause TSC page value to go very big because of a signedness issue around hv_clock->system_time. Signed-off-by: Vitaly Kuznetsov Message-Id: <20210326155551.17446-3-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/x86_64/hyperv_clock.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c index ffbc4555c6e2..7f1d2765572c 100644 --- a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c +++ b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c @@ -80,19 +80,24 @@ static inline void check_tsc_msr_rdtsc(void) GUEST_ASSERT(delta_ns * 100 < (t2 - t1) * 100); } +static inline u64 get_tscpage_ts(struct ms_hyperv_tsc_page *tsc_page) +{ + return mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset; +} + static inline void check_tsc_msr_tsc_page(struct ms_hyperv_tsc_page *tsc_page) { u64 r1, r2, t1, t2; /* Compare TSC page clocksource with HV_X64_MSR_TIME_REF_COUNT */ - t1 = mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset; + t1 = get_tscpage_ts(tsc_page); r1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); /* 10 ms tolerance */ GUEST_ASSERT(r1 >= t1 && r1 - t1 < 100000); nop_loop(); - t2 = mul_u64_u64_shr64(rdtsc(), tsc_page->tsc_scale) + tsc_page->tsc_offset; + t2 = get_tscpage_ts(tsc_page); r2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); GUEST_ASSERT(r2 >= t1 && r2 - t2 < 100000); } @@ -130,7 +135,11 @@ static void guest_main(struct ms_hyperv_tsc_page *tsc_page, vm_paddr_t tsc_page_ tsc_offset = tsc_page->tsc_offset; /* Call KVM_SET_CLOCK from userspace, check that TSC page was updated */ + GUEST_SYNC(7); + /* Sanity check TSC page timestamp, it should be close to 0 */ + GUEST_ASSERT(get_tscpage_ts(tsc_page) < 100000); + GUEST_ASSERT(tsc_page->tsc_offset != tsc_offset); nop_loop();