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KVM: arm64: Don't clobber x4 in __do_hyp_init

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arm_smccc_1_1_hvc() only adds write contraints for x0-3 in the inline
assembly for the HVC instruction so make sure those are the only
registers that change when __do_hyp_init is called.

Tested-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Andrew Scull <ascull@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210125145415.122439-3-ascull@google.com
This commit is contained in:
Andrew Scull 2021-01-25 14:54:15 +00:00 committed by Marc Zyngier
parent 139bc8a614
commit e500b805c3
1 changed files with 11 additions and 9 deletions
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20
arch/arm64/kvm/hyp/nvhe/hyp-init.S
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@ -47,6 +47,8 @@ __invalid:
b .
/*
* Only uses x0..x3 so as to not clobber callee-saved SMCCC registers.
*
* x0: SMCCC function ID
* x1: struct kvm_nvhe_init_params PA
*/
@ -70,9 +72,9 @@ __do_hyp_init:
eret
1: mov x0, x1
mov x4, lr
bl ___kvm_hyp_init
mov lr, x4
mov x3, lr
bl ___kvm_hyp_init // Clobbers x0..x2
mov lr, x3
/* Hello, World! */
mov x0, #SMCCC_RET_SUCCESS
@ -82,8 +84,8 @@ SYM_CODE_END(__kvm_hyp_init)
/*
* Initialize the hypervisor in EL2.
*
* Only uses x0..x3 so as to not clobber callee-saved SMCCC registers
* and leave x4 for the caller.
* Only uses x0..x2 so as to not clobber callee-saved SMCCC registers
* and leave x3 for the caller.
*
* x0: struct kvm_nvhe_init_params PA
*/
@ -112,9 +114,9 @@ alternative_else_nop_endif
/*
* Set the PS bits in TCR_EL2.
*/
ldr x1, [x0, #NVHE_INIT_TCR_EL2]
tcr_compute_pa_size x1, #TCR_EL2_PS_SHIFT, x2, x3
msr tcr_el2, x1
ldr x0, [x0, #NVHE_INIT_TCR_EL2]
tcr_compute_pa_size x0, #TCR_EL2_PS_SHIFT, x1, x2
msr tcr_el2, x0
isb
@ -193,7 +195,7 @@ SYM_CODE_START_LOCAL(__kvm_hyp_init_cpu)
/* Enable MMU, set vectors and stack. */
mov x0, x28
bl ___kvm_hyp_init // Clobbers x0..x3
bl ___kvm_hyp_init // Clobbers x0..x2
/* Leave idmap. */
mov x0, x29