Messages in this thread | | | Subject | Re: [PATCH 4/7] x86/microcode: Do not upload microcode if CPUs are offline | From | Tom Lendacky <> | Date | Mon, 5 Mar 2018 16:06:48 -0600 |
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On 2/28/2018 4:28 AM, Borislav Petkov wrote: > From: Ashok Raj <ashok.raj@intel.com> > > Avoid loading microcode if any of the CPUs are offline, and issue a > warning. Having different microcode revisions on the system at any time > is outright dangerous. > > Signed-off-by: Ashok Raj <ashok.raj@intel.com> > Cc: x86-ml <x86@kernel.org> > Link: http://lkml.kernel.org/r/1519352533-15992-4-git-send-email-ashok.raj@intel.com > [ Massage it. ] > Signed-off-by: Borislav Petkov <bp@suse.de> > --- > arch/x86/kernel/cpu/microcode/core.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) >
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c > index 63370651e376..fa32cb3dcca5 100644 > --- a/arch/x86/kernel/cpu/microcode/core.c > +++ b/arch/x86/kernel/cpu/microcode/core.c > @@ -486,6 +486,16 @@ static void __exit microcode_dev_exit(void) > /* fake device for request_firmware */ > static struct platform_device *microcode_pdev; > > +static int check_online_cpus(void) > +{ > + if (num_online_cpus() == num_present_cpus()) > + return 0; > + > + pr_err("Not all CPUs online, aborting microcode update.\n"); > + > + return -EINVAL; > +} > + > static enum ucode_state reload_for_cpu(int cpu) > { > struct ucode_cpu_info *uci = ucode_cpu_info + cpu; > @@ -519,7 +529,13 @@ static ssize_t reload_store(struct device *dev, > return size; > > get_online_cpus(); > + > + ret = check_online_cpus(); > + if (ret) > + goto put; > + > mutex_lock(µcode_mutex); > + > for_each_online_cpu(cpu) { > tmp_ret = reload_for_cpu(cpu); > if (tmp_ret > UCODE_NFOUND) { > @@ -538,6 +554,8 @@ static ssize_t reload_store(struct device *dev, > microcode_check(); > > mutex_unlock(µcode_mutex); > + > +put: > put_online_cpus(); > > if (!ret) >
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