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KVM: arm64: Generate final CTR_EL0 value when running in Protected mode

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In protected mode, late CPUs are not allowed to boot (enforced by
the PSCI relay). We can thus specialise the read_ctr macro to
always return a pre-computed, sanitised value. Special care is
taken to prevent the use of this custome version outside of
the protected mode.

Reviewed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2021-03-22 12:09:51 +00:00
parent 90134ac9ca
commit 755db23420
3 changed files with 21 additions and 0 deletions
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13
arch/arm64/include/asm/assembler.h
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@ -15,6 +15,7 @@
#include <asm-generic/export.h> #include <asm-generic/export.h>
#include <asm/asm-offsets.h> #include <asm/asm-offsets.h>
#include <asm/asm-bug.h>
#include <asm/cpufeature.h> #include <asm/cpufeature.h>
#include <asm/cputype.h> #include <asm/cputype.h>
#include <asm/debug-monitors.h> #include <asm/debug-monitors.h>
@ -270,12 +271,24 @@ alternative_endif
* provide the system wide safe value from arm64_ftr_reg_ctrel0.sys_val * provide the system wide safe value from arm64_ftr_reg_ctrel0.sys_val
*/ */
.macro read_ctr, reg .macro read_ctr, reg
#ifndef __KVM_NVHE_HYPERVISOR__
alternative_if_not ARM64_MISMATCHED_CACHE_TYPE alternative_if_not ARM64_MISMATCHED_CACHE_TYPE
mrs \reg, ctr_el0 // read CTR mrs \reg, ctr_el0 // read CTR
nop nop
alternative_else alternative_else
ldr_l \reg, arm64_ftr_reg_ctrel0 + ARM64_FTR_SYSVAL ldr_l \reg, arm64_ftr_reg_ctrel0 + ARM64_FTR_SYSVAL
alternative_endif alternative_endif
#else
alternative_if_not ARM64_KVM_PROTECTED_MODE
ASM_BUG()
alternative_else_nop_endif
alternative_cb kvm_compute_final_ctr_el0
movz \reg, #0
movk \reg, #0, lsl #16
movk \reg, #0, lsl #32
movk \reg, #0, lsl #48
alternative_cb_end
#endif
.endm .endm

1
arch/arm64/kernel/image-vars.h
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@ -65,6 +65,7 @@ __efistub__ctype = _ctype;
KVM_NVHE_ALIAS(kvm_patch_vector_branch); KVM_NVHE_ALIAS(kvm_patch_vector_branch);
KVM_NVHE_ALIAS(kvm_update_va_mask); KVM_NVHE_ALIAS(kvm_update_va_mask);
KVM_NVHE_ALIAS(kvm_get_kimage_voffset); KVM_NVHE_ALIAS(kvm_get_kimage_voffset);
KVM_NVHE_ALIAS(kvm_compute_final_ctr_el0);
/* Global kernel state accessed by nVHE hyp code. */ /* Global kernel state accessed by nVHE hyp code. */
KVM_NVHE_ALIAS(kvm_vgic_global_state); KVM_NVHE_ALIAS(kvm_vgic_global_state);

7
arch/arm64/kvm/va_layout.c
View File

@ -288,3 +288,10 @@ void kvm_get_kimage_voffset(struct alt_instr *alt,
{ {
generate_mov_q(kimage_voffset, origptr, updptr, nr_inst); generate_mov_q(kimage_voffset, origptr, updptr, nr_inst);
} }
void kvm_compute_final_ctr_el0(struct alt_instr *alt,
__le32 *origptr, __le32 *updptr, int nr_inst)
{
generate_mov_q(read_sanitised_ftr_reg(SYS_CTR_EL0),
origptr, updptr, nr_inst);
}