Forward traps due to FP/ASIMD register accesses to the virtual EL2 if virtual CPTR_EL2.TFP is set. Note that if TFP bit is set, then even accesses to FP/ASIMD register from EL2 as well as NS EL0/1 will trap to EL2. So, we don't check the VM's exception level.
Signed-off-by: Jintack Lim <jintack....@linaro.org> --- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/handle_exit.c | 15 +++++++++++---- arch/arm64/kvm/hyp/entry.S | 13 +++++++++++++ arch/arm64/kvm/hyp/hyp-entry.S | 2 +- 4 files changed, 26 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index b3bb7ef..f5117a3 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -134,6 +134,7 @@ int main(void) DEFINE(CPU_FP_REGS, offsetof(struct kvm_regs, fp_regs)); DEFINE(VCPU_FPEXC32_EL2, offsetof(struct kvm_vcpu, arch.ctxt.sys_regs[FPEXC32_EL2])); DEFINE(VCPU_HOST_CONTEXT, offsetof(struct kvm_vcpu, arch.host_cpu_context)); + DEFINE(VIRTUAL_CPTR_EL2, offsetof(struct kvm_vcpu, arch.ctxt.sys_regs[CPTR_EL2])); #endif #ifdef CONFIG_CPU_PM DEFINE(CPU_SUSPEND_SZ, sizeof(struct cpu_suspend_ctx)); diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 25ec824..d4e7b2b 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -84,11 +84,18 @@ static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run) } /* - * Guest access to FP/ASIMD registers are routed to this handler only - * when the system doesn't support FP/ASIMD. + * When the system supports FP/ASMID and we are NOT running nested + * virtualization, FP/ASMID traps are handled in EL2 directly. + * This handler handles the cases those are not belong to the above case. */ -static int handle_no_fpsimd(struct kvm_vcpu *vcpu, struct kvm_run *run) +static int kvm_handle_fpasimd(struct kvm_vcpu *vcpu, struct kvm_run *run) { + + /* This is for nested virtualization */ + if (vcpu_sys_reg(vcpu, CPTR_EL2) & CPTR_EL2_TFP) + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu)); + + /* This is the case when the system doesn't support FP/ASIMD. */ kvm_inject_undefined(vcpu); return 1; } @@ -220,7 +227,7 @@ static int kvm_handle_eret(struct kvm_vcpu *vcpu, struct kvm_run *run) [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, + [ESR_ELx_EC_FP_ASIMD] = kvm_handle_fpasimd, }; static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu) diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 12ee62d..95af673 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -158,6 +158,19 @@ abort_guest_exit_end: 1: ret ENDPROC(__guest_exit) +ENTRY(__fpsimd_guest_trap) + // If virtual CPTR_EL2.TFP is set, then forward the trap to the + // virtual EL2. For the non-nested case, this bit is always 0. + mrs x1, tpidr_el2 + ldr x0, [x1, #VIRTUAL_CPTR_EL2] + and x0, x0, #CPTR_EL2_TFP + cbnz x0, 1f + b __fpsimd_guest_restore +1: + mov x0, #ARM_EXCEPTION_TRAP + b __guest_exit +ENDPROC(__fpsimd_guest_trap) + ENTRY(__fpsimd_guest_restore) stp x2, x3, [sp, #-16]! stp x4, lr, [sp, #-16]! diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 5170ce1..ab169fd 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -113,7 +113,7 @@ el1_trap: */ alternative_if_not ARM64_HAS_NO_FPSIMD cmp x0, #ESR_ELx_EC_FP_ASIMD - b.eq __fpsimd_guest_restore + b.eq __fpsimd_guest_trap alternative_else_nop_endif mrs x1, tpidr_el2 -- 1.9.1