Commit b81125c7 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

arm64: KVM: VHE: Patch out use of HVC



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.
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 1e947bad
......@@ -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)
......@@ -38,6 +38,34 @@
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].
*/
sub sp, sp, #16
str lr, [sp]
mov lr, x0
mov x0, x1
mov x1, x2
mov x2, x3
blr lr
ldr lr, [sp]
add sp, 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.
*/
isb
ret
ENDPROC(__vhe_hyp_call)
el1_sync: // Guest trapped into EL2
save_x0_to_x3
......@@ -58,19 +86,13 @@ 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:
......
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