From: Like Xu like.xu@linux.intel.com
commit e61ab2a320c3dfd6209efe18a575979e07470597 upstream.
Since we know vPMU will not work properly when (1) the guest bit_width(s) of the [gp|fixed] counters are greater than the host ones, or (2) guest requested architectural events exceeds the range supported by the host, so we can setup a smaller left shift value and refresh the guest cpuid entry, thus fixing the following UBSAN shift-out-of-bounds warning:
shift exponent 197 is too large for 64-bit type 'long long unsigned int'
Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395 intel_pmu_refresh.cold+0x75/0x99 arch/x86/kvm/vmx/pmu_intel.c:348 kvm_vcpu_after_set_cpuid+0x65a/0xf80 arch/x86/kvm/cpuid.c:177 kvm_vcpu_ioctl_set_cpuid2+0x160/0x440 arch/x86/kvm/cpuid.c:308 kvm_arch_vcpu_ioctl+0x11b6/0x2d70 arch/x86/kvm/x86.c:4709 kvm_vcpu_ioctl+0x7b9/0xdb0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3386 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reported-by: syzbot+ae488dc136a4cc6ba32b@syzkaller.appspotmail.com Signed-off-by: Like Xu like.xu@linux.intel.com Message-Id: 20210118025800.34620-1-like.xu@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kvm/vmx/pmu_intel.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -296,7 +296,9 @@ static void intel_pmu_refresh(struct kvm
pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters, x86_pmu.num_counters_gp); + eax.split.bit_width = min_t(int, eax.split.bit_width, x86_pmu.bit_width_gp); pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << eax.split.bit_width) - 1; + eax.split.mask_length = min_t(int, eax.split.mask_length, x86_pmu.events_mask_len); pmu->available_event_types = ~entry->ebx & ((1ull << eax.split.mask_length) - 1);
@@ -306,6 +308,8 @@ static void intel_pmu_refresh(struct kvm pmu->nr_arch_fixed_counters = min_t(int, edx.split.num_counters_fixed, x86_pmu.num_counters_fixed); + edx.split.bit_width_fixed = min_t(int, + edx.split.bit_width_fixed, x86_pmu.bit_width_fixed); pmu->counter_bitmask[KVM_PMC_FIXED] = ((u64)1 << edx.split.bit_width_fixed) - 1; }