On Mon, Jan 25, 2016 at 03:53:40PM +0000, Marc Zyngier wrote: > With VHE, the host never issues an HVC instruction to get into the > KVM code, as we can simply branch there. > > Use runtime code patching to simplify things a bit. > > Signed-off-by: Marc Zyngier <[email protected]> > --- > arch/arm64/kvm/hyp.S | 7 +++++++ > arch/arm64/kvm/hyp/hyp-entry.S | 38 +++++++++++++++++++++++++++++--------- > 2 files changed, 36 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index 0ccdcbb..0689a74 100644 > --- a/arch/arm64/kvm/hyp.S > +++ b/arch/arm64/kvm/hyp.S > @@ -17,7 +17,9 @@ > > #include <linux/linkage.h> > > +#include <asm/alternative.h> > #include <asm/assembler.h> > +#include <asm/cpufeature.h> > > /* > * u64 kvm_call_hyp(void *hypfn, ...); > @@ -38,6 +40,11 @@ > * arch/arm64/kernel/hyp_stub.S. > */ > ENTRY(kvm_call_hyp) > +alternative_if_not ARM64_HAS_VIRT_HOST_EXTN > hvc #0 > ret > +alternative_else > + b __vhe_hyp_call > + nop > +alternative_endif > ENDPROC(kvm_call_hyp) > diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S > index 93e8d983..9e0683f 100644 > --- a/arch/arm64/kvm/hyp/hyp-entry.S > +++ b/arch/arm64/kvm/hyp/hyp-entry.S > @@ -38,6 +38,32 @@ > ldp x0, x1, [sp], #16 > .endm > > +.macro do_el2_call > + /* > + * Shuffle the parameters before calling the function > + * pointed to in x0. Assumes parameters in x[1,2,3]. > + */ > + stp lr, xzr, [sp, #-16]!
remind me why this pair isn't just doing "str" instead of "stp" with the xzr ? > + mov lr, x0 > + mov x0, x1 > + mov x1, x2 > + mov x2, x3 > + blr lr > + ldp lr, xzr, [sp], #16 > +.endm > + > +ENTRY(__vhe_hyp_call) > + do_el2_call > + /* > + * We used to rely on having an exception return to get > + * an implicit isb. In the E2H case, we don't have it anymore. > + * rather than changing all the leaf functions, just do it here > + * before returning to the rest of the kernel. > + */ why is this not the case with an ISB before do_el2_call then? > + isb > + ret > +ENDPROC(__vhe_hyp_call) > + > el1_sync: // Guest trapped into EL2 > save_x0_to_x3 > > @@ -58,19 +84,13 @@ el1_sync: // Guest trapped into > EL2 > mrs x0, vbar_el2 > b 2f > > -1: stp lr, xzr, [sp, #-16]! > - > +1: > /* > - * Compute the function address in EL2, and shuffle the parameters. > + * Perform the EL2 call > */ > kern_hyp_va x0 > - mov lr, x0 > - mov x0, x1 > - mov x1, x2 > - mov x2, x3 > - blr lr > + do_el2_call > > - ldp lr, xzr, [sp], #16 > 2: eret > > el1_trap: > -- > 2.1.4 >
