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arm64: KVM: VHE: Patch out use of HVC

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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: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit b81125c791)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
This commit is contained in:
Marc Zyngier
2015-01-29 13:52:12 +00:00
committed by Alex Shi
parent 45f5d7f2ea
commit 493f9d8798
2 changed files with 38 additions and 9 deletions
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7
arch/arm64/kvm/hyp.S
View File

@@ -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)

40
arch/arm64/kvm/hyp/hyp-entry.S
View File

@@ -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: