diff options
| author | Suzuki K Poulose <suzuki.poulose@arm.com> | 2016-11-08 13:56:21 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-16 18:05:10 +0000 |
| commit | 82e0191a1aa11abfddb22c8944989b7735560efc (patch) | |
| tree | 192b21e7191e2385dc4a58f0562fff4a2f5f68b4 /arch/arm64/kvm | |
| parent | a4023f682739439b434165b54af7cb3676a4766e (diff) | |
arm64: Support systems without FP/ASIMD
The arm64 kernel assumes that FP/ASIMD units are always present
and accesses the FP/ASIMD specific registers unconditionally. This
could cause problems when they are absent. This patch adds the
support for kernel handling systems without FP/ASIMD by skipping the
register access within the kernel. For kvm, we trap the accesses
to FP/ASIMD and inject an undefined instruction exception to the VM.
The callers of the exported kernel_neon_begin_partial() should
make sure that the FP/ASIMD is supported.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
[catalin.marinas@arm.com: add comment on the ARM64_HAS_NO_FPSIMD conflict and the new location]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kvm')
| -rw-r--r-- | arch/arm64/kvm/handle_exit.c | 11 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/hyp-entry.S | 9 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/switch.c | 5 |
3 files changed, 23 insertions, 2 deletions
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index a204adf29f0a..1bfe30dfbfe7 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -57,6 +57,16 @@ static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) return 1; } +/* + * Guest access to FP/ASIMD registers are routed to this handler only + * when the system doesn't support FP/ASIMD. + */ +static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run) +{ + kvm_inject_undefined(vcpu); + return 1; +} + /** * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event * instruction executed by a guest @@ -144,6 +154,7 @@ static exit_handle_fn arm_exit_handlers[] = { [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug, [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug, [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug, + [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd, }; static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 4e92399f7105..5e9052f087f2 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -106,9 +106,16 @@ el1_trap: * x0: ESR_EC */ - /* Guest accessed VFP/SIMD registers, save host, restore Guest */ + /* + * We trap the first access to the FP/SIMD to save the host context + * and restore the guest context lazily. + * If FP/SIMD is not implemented, handle the trap and inject an + * undefined instruction exception to the guest. + */ +alternative_if_not ARM64_HAS_NO_FPSIMD cmp x0, #ESR_ELx_EC_FP_ASIMD b.eq __fpsimd_guest_restore +alternative_else_nop_endif mrs x1, tpidr_el2 mov x0, #ARM_EXCEPTION_TRAP diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 83037cd62d01..8bcae7b14704 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -21,6 +21,7 @@ #include <asm/kvm_asm.h> #include <asm/kvm_emulate.h> #include <asm/kvm_hyp.h> +#include <asm/fpsimd.h> static bool __hyp_text __fpsimd_enabled_nvhe(void) { @@ -76,9 +77,11 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu) * traps are only taken to EL2 if the operation would not otherwise * trap to EL1. Therefore, always make sure that for 32-bit guests, * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit. + * If FP/ASIMD is not implemented, FPEXC is UNDEFINED and any access to + * it will cause an exception. */ val = vcpu->arch.hcr_el2; - if (!(val & HCR_RW)) { + if (!(val & HCR_RW) && system_supports_fpsimd()) { write_sysreg(1 << 30, fpexc32_el2); isb(); } |