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Fix divide by zero on host TSC calibration failure (rhbz 859282)

This commit is contained in:
Josh Boyer 2013-03-14 07:45:49 -04:00
parent ba0e8b1ec4
commit 2fffaa5d9f
2 changed files with 68 additions and 2 deletions
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58
VMX-x86-handle-host-TSC-calibration-failure.patch Normal file
View File

@ -0,0 +1,58 @@
@@ -, +, @@
VMX: x86: handle host TSC calibration failure
If the host TSC calibration fails, tsc_khz is zero (see tsc_init.c).
Handle such case properly in KVM (instead of dividing by zero).
https://bugzilla.redhat.com/show_bug.cgi?id=859282
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
--- a/arch/x86/kvm/x86.c
+++ a/arch/x86/kvm/x86.c
@@ -1079,6 +1079,10 @@ static void kvm_set_tsc_khz(struct kvm_vcpu *vcpu, u32 this_tsc_khz)
u32 thresh_lo, thresh_hi;
int use_scaling = 0;
+ /* tsc_khz can be zero if TSC calibration fails */
+ if (this_tsc_khz == 0)
+ return;
+
/* Compute a scale to convert nanoseconds in TSC cycles */
kvm_get_time_scale(this_tsc_khz, NSEC_PER_SEC / 1000,
&vcpu->arch.virtual_tsc_shift,
@@ -1156,20 +1160,23 @@ void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
ns = get_kernel_ns();
elapsed = ns - kvm->arch.last_tsc_nsec;
- /* n.b - signed multiplication and division required */
- usdiff = data - kvm->arch.last_tsc_write;
+ if (vcpu->arch.virtual_tsc_khz) {
+ /* n.b - signed multiplication and division required */
+ usdiff = data - kvm->arch.last_tsc_write;
#ifdef CONFIG_X86_64
- usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
+ usdiff = (usdiff * 1000) / vcpu->arch.virtual_tsc_khz;
#else
- /* do_div() only does unsigned */
- asm("idivl %2; xor %%edx, %%edx"
- : "=A"(usdiff)
- : "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
+ /* do_div() only does unsigned */
+ asm("idivl %2; xor %%edx, %%edx"
+ : "=A"(usdiff)
+ : "A"(usdiff * 1000), "rm"(vcpu->arch.virtual_tsc_khz));
#endif
- do_div(elapsed, 1000);
- usdiff -= elapsed;
- if (usdiff < 0)
- usdiff = -usdiff;
+ do_div(elapsed, 1000);
+ usdiff -= elapsed;
+ if (usdiff < 0)
+ usdiff = -usdiff;
+ } else
+ usdiff = USEC_PER_SEC; /* disable TSC match window below */
/*
* Special case: TSC write with a small delta (1 second) of virtual

12
kernel.spec
View File

@ -62,7 +62,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be appended after the rcX and
# gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
#
%global baserelease 1
%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -740,6 +740,9 @@ Patch21271: drm-i915-bounds-check-execbuffer-relocation-count.patch
Patch21273: cfg80211-mac80211-disconnect-on-suspend.patch
Patch21274: mac80211_fixes_for_ieee80211_do_stop_while_suspend_v3.9.patch
#rhbz 859282
Patch21275: VMX-x86-handle-host-TSC-calibration-failure.patch
Patch22000: weird-root-dentry-name-debug.patch
#selinux ptrace child permissions
@ -1438,6 +1441,9 @@ ApplyPatch drm-i915-bounds-check-execbuffer-relocation-count.patch
ApplyPatch cfg80211-mac80211-disconnect-on-suspend.patch
ApplyPatch mac80211_fixes_for_ieee80211_do_stop_while_suspend_v3.9.patch
#rhbz 859282
ApplyPatch VMX-x86-handle-host-TSC-calibration-failure.patch
# END OF PATCH APPLICATIONS
%endif
@ -2270,11 +2276,13 @@ fi
# and build.
%changelog
* Fri Mar 15 2013 Josh Boyer <jwboyer@redhat.com>
- Fix divide by zero on host TSC calibration failure (rhbz 859282)
* Fri Mar 15 2013 Josh Boyer <jwboyer@redhat.com> - 3.9.0-0.rc2.git1.1
- Linux v3.9-rc2-292-ga2362d2
- Fixes CVE-2013-1860 kernel: usb: cdc-wdm buffer overflow triggered by device
* Wed Mar 13 2013 Dave Jones <davej@redhat.com> - 3.9.0-0.rc2.git0.3
- Reenable debugging options.