[SRU][Xenial][PATCH 2/2] UBUNTU: SAUCE: hv: don't reset hv_context.tsc_page on crash

[Joseph Salisbury]

On 01/27/2017 02:56 PM, Joseph Salisbury wrote:
> From: Vitaly Kuznetsov <vkuznets at redhat.com>
>
> BugLink: http://bugs.launchpad.net/bugs/1630924
>
> It may happen that secondary CPUs are still alive and resetting
> hv_context.tsc_page will cause a consequent crash in read_hv_clock_tsc()
> as we don't check for it being not NULL there. It is safe as we're not
> freeing this page anyways.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets at redhat.com>
> Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
> Cc: <stable at vger.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (cherry picked from commit 56ef6718a1d8d77745033c5291e025ce18504159)
> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
> ---
>  drivers/hv/hv.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index ab1f466..60db5ff 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -317,9 +317,10 @@ void hv_cleanup(bool crash)
>  
>  		hypercall_msr.as_uint64 = 0;
>  		wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
> -		if (!crash)
> +		if (!crash) {
>  			vfree(hv_context.tsc_page);
> -		hv_context.tsc_page = NULL;
> +			hv_context.tsc_page = NULL;
> +		}
>  	}
>  #endif
>  }

I guess this doesn't need to be SAUCE since it's in linux-next.