On Sun, 19 Feb 2017 08:07:22 +0000 Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > On 17 February 2017 at 15:44, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > > In order to restore HYP mode to its original condition, KVM currently > > implements __kvm_hyp_reset(). As we're moving towards a hyp-stub > > defined API, it becomes necessary to implement HVC_RESET_VECTORS. > > > > This patch adds the HVC_RESET_VECTORS hypercall to the KVM init > > code, which so far lacked any form of hypercall support. > > > > Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > > --- > > arch/arm/kernel/hyp-stub.S | 1 + > > arch/arm/kvm/init.S | 37 +++++++++++++++++++++++++++++++------ > > 2 files changed, 32 insertions(+), 6 deletions(-) > > > > diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S > > index cf6d801f89e8..171a09cdf6b3 100644 > > --- a/arch/arm/kernel/hyp-stub.S > > +++ b/arch/arm/kernel/hyp-stub.S > > @@ -280,6 +280,7 @@ ENDPROC(__hyp_reset_vectors) > > > > .align 5 > > __hyp_stub_vectors: > > +.global __hyp_stub_vectors > > __hyp_stub_reset: W(b) . > > __hyp_stub_und: W(b) . > > __hyp_stub_svc: W(b) . > > diff --git a/arch/arm/kvm/init.S b/arch/arm/kvm/init.S > > index bf89c919efc1..b0138118fac4 100644 > > --- a/arch/arm/kvm/init.S > > +++ b/arch/arm/kvm/init.S > > @@ -23,6 +23,7 @@ > > #include <asm/kvm_asm.h> > > #include <asm/kvm_arm.h> > > #include <asm/kvm_mmu.h> > > +#include <asm/virt.h> > > > > /******************************************************************** > > * Hypervisor initialization > > @@ -39,6 +40,10 @@ > > * - Setup the page tables > > * - Enable the MMU > > * - Profit! (or eret, if you only care about the code). > > + * > > + * Another possibility is to get a HYP stub hypercall. > > + * We discriminate between the two by checking if r0 contains a value > > + * that is less than HVC_STUB_HCALL_NR. > > */ > > > > .text > > @@ -58,6 +63,10 @@ __kvm_hyp_init: > > W(b) . > > > > __do_hyp_init: > > + @ Check for a stub hypercall > > + cmp r0, #HVC_STUB_HCALL_NR > > + blo __kvm_handle_stub_hvc > > + > > @ Set stack pointer > > mov sp, r0 > > > > @@ -112,22 +121,38 @@ __do_hyp_init: > > > > eret > > > > - @ r0 : stub vectors address > > +ENTRY(__kvm_handle_stub_hvc) > > + cmp r0, #HVC_RESET_VECTORS > > + bne 1f > > ENTRY(__kvm_hyp_reset) > > /* We're now in idmap, disable MMU */ > > mrc p15, 4, r1, c1, c0, 0 @ HSCTLR > > - ldr r2, =(HSCTLR_M | HSCTLR_A | HSCTLR_C | HSCTLR_I) > > - bic r1, r1, r2 > > + ldr r0, =(HSCTLR_M | HSCTLR_A | HSCTLR_C | HSCTLR_I) > > + bic r1, r1, r0 > > mcr p15, 4, r1, c1, c0, 0 @ HSCTLR > > > > - /* Install stub vectors */ > > - mcr p15, 4, r0, c12, c0, 0 @ HVBAR > > - isb > > + /* > > + * Install stub vectors. We cannot use 'adr' to get to the > > + * stub vectors, hence having to play the VA->PA game. > > + */ > > + adr r0, .L__va2pa @ PA > > + ldr r1, [r0] @ VA > > + sub r0, r0, r1 @ PA - VA > > + ldr r1, =__hyp_stub_vectors > > Since we're guaranteed to be on v7, how about something like > 0:adr r0, 0b > movw r1, #:lower16:__hyp_stub_vectors - 0b > movt r1, #:upper16:__hyp_stub_vectors - 0b Ah, very nice! It hurts my brain, but it is very nice indeed! I'll borrow that for v2. Thanks, M. -- Without deviation from the norm, progress is not possible.
