On Tue, 05 Jan 2021 20:35:35 +0000, Jing Zhang <jingzhangos@xxxxxxxxxx> wrote: > > On Mon, Jan 4, 2021 at 7:50 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > As we are about to change the way a VHE system boots, let's > > provide the core helper, in the form of a stub hypercall that > > enables VHE and replicates the full EL1 context at EL2, thanks > > to EL1 and VHE-EL2 being extremely similar. > > > > On exception return, the kernel carries on at EL2. Fancy! > > > > Nothing calls this new hypercall yet, so no functional change. > > > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > > --- > > arch/arm64/include/asm/virt.h | 7 +++- > > arch/arm64/kernel/hyp-stub.S | 70 ++++++++++++++++++++++++++++++++++- > > 2 files changed, 74 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h > > index ee6a48df89d9..7379f35ae2c6 100644 > > --- a/arch/arm64/include/asm/virt.h > > +++ b/arch/arm64/include/asm/virt.h > > @@ -35,8 +35,13 @@ > > */ > > #define HVC_RESET_VECTORS 2 > > > > +/* > > + * HVC_VHE_RESTART - Upgrade the CPU from EL1 to EL2, if possible > > + */ > > +#define HVC_VHE_RESTART 3 > > + > > /* Max number of HYP stub hypercalls */ > > -#define HVC_STUB_HCALL_NR 3 > > +#define HVC_STUB_HCALL_NR 4 > > > > /* Error returned when an invalid stub number is passed into x0 */ > > #define HVC_STUB_ERR 0xbadca11 > > diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S > > index 160f5881a0b7..6ffdc1f7778b 100644 > > --- a/arch/arm64/kernel/hyp-stub.S > > +++ b/arch/arm64/kernel/hyp-stub.S > > @@ -8,9 +8,9 @@ > > > > #include <linux/init.h> > > #include <linux/linkage.h> > > -#include <linux/irqchip/arm-gic-v3.h> > > > > #include <asm/assembler.h> > > +#include <asm/el2_setup.h> > > #include <asm/kvm_arm.h> > > #include <asm/kvm_asm.h> > > #include <asm/ptrace.h> > > @@ -47,10 +47,16 @@ SYM_CODE_END(__hyp_stub_vectors) > > > > SYM_CODE_START_LOCAL(el1_sync) > > cmp x0, #HVC_SET_VECTORS > > - b.ne 2f > > + b.ne 1f > > msr vbar_el2, x1 > > b 9f > > > > +1: cmp x0, #HVC_VHE_RESTART > > + b.ne 2f > > + mov x0, #HVC_SOFT_RESTART > > + adr x1, mutate_to_vhe > > + // fall through... > Does "br x1" work here instead of falling through into > HVC_SOFT_RESTART? Just curious about the reason for falling-through. Absolutely. This is the leftover from an initial (and pretty over-engineered) approach where the caller was using HVC_SOFT_RESTART with the address of mutate_to_vhe passed as the target. It was an interesting idea, but obtaining the PA for the function ended when the MMU is on created a separate, harder to maintain path. Cleanup time, I guess. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
