[PATCH 7/8] arm64/kexec: Add checks for KVM

[geoff@infradead.org (Geoff Levand)]

On Mon, 2015-01-26 at 21:39 +0100, Christoffer Dall wrote:
> On Mon, Jan 26, 2015 at 8:19 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Sat, Jan 17, 2015 at 12:23:34AM +0000, Geoff Levand wrote:
> >> Add runtime checks that fail the arm64 kexec syscall for situations that would
> >> result in system instability do to problems in the KVM kernel support.
> >> These checks should be removed when the KVM problems are resolved fixed.
> >>
> >> Signed-off-by: Geoff Levand <geoff@infradead.org>
> >> ---
> >>  arch/arm64/kernel/machine_kexec.c | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> >> index 3d84759..a36459d 100644
> >> --- a/arch/arm64/kernel/machine_kexec.c
> >> +++ b/arch/arm64/kernel/machine_kexec.c
> >> @@ -16,6 +16,9 @@
> >>  #include <asm/cacheflush.h>
> >>  #include <asm/system_misc.h>
> >>
> >> +/* TODO: Remove this include when KVM can support a kexec reboot. */
> >> +#include <asm/virt.h>
> >> +
> >>  /* Global variables for the relocate_kernel routine. */
> >>  extern const unsigned char relocate_new_kernel[];
> >>  extern const unsigned long relocate_new_kernel_size;
> >> @@ -100,6 +103,13 @@ int machine_kexec_prepare(struct kimage *image)
> >>
> >>       kexec_image_info(image);
> >>
> >> +     /* TODO: Remove this message when KVM can support a kexec reboot. */
> >> +     if (IS_ENABLED(CONFIG_KVM) && is_hyp_mode_available()) {
> >> +             pr_err("%s: Your kernel is configured with KVM support (CONFIG_KVM=y) which currently does not allow for kexec re-boot.\n",
> >> +                     __func__);
> >> +             return -ENOSYS;
> >> +     }
> >
> > If you really don't want to implement KVM teardown, surely this should
> > be at the start of the series, so we don't have a point in the middle
> > where things may explode in this case?
> >
> So this caters to support systems that don't support KVM (don't boot
> in EL2) but is configured with both KVM and KEXEC?
> 
> Why not just make the kexec config dependent on !KVM ?

Sure, that would work.  I put it this way so we can get build testing of
kexec since the arm64 defconfig has KVM set.

-Geoff