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Re: [Qemu-devel] [PATCH v3 13/16] target-arm: A64: Emulate the HVC insn
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH v3 13/16] target-arm: A64: Emulate the HVC insn |
Date: |
Fri, 1 Aug 2014 15:21:08 +0100 |
On 17 June 2014 09:45, Edgar E. Iglesias <address@hidden> wrote:
> From: "Edgar E. Iglesias" <address@hidden>
>
> Signed-off-by: Edgar E. Iglesias <address@hidden>
> ---
> target-arm/cpu.h | 1 +
> target-arm/helper-a64.c | 1 +
> target-arm/helper.c | 28 +++++++++++++++++++++++++++-
> target-arm/helper.h | 1 +
> target-arm/internals.h | 6 ++++++
> target-arm/op_helper.c | 33 +++++++++++++++++++++++++++++++++
> target-arm/translate-a64.c | 21 ++++++++++++++++-----
> 7 files changed, 85 insertions(+), 6 deletions(-)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index 4f273ac..258bc09 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -51,6 +51,7 @@
> #define EXCP_EXCEPTION_EXIT 8 /* Return from v7M exception. */
> #define EXCP_KERNEL_TRAP 9 /* Jumped to kernel code page. */
> #define EXCP_STREX 10
> +#define EXCP_HVC 11 /* HyperVisor Call */
>
> #define ARMV7M_EXCP_RESET 1
> #define ARMV7M_EXCP_NMI 2
> diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
> index cf8ce1e..7382d0a 100644
> --- a/target-arm/helper-a64.c
> +++ b/target-arm/helper-a64.c
> @@ -475,6 +475,7 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
> case EXCP_BKPT:
> case EXCP_UDEF:
> case EXCP_SWI:
> + case EXCP_HVC:
> env->cp15.esr_el[new_el] = env->exception.syndrome;
> break;
> case EXCP_IRQ:
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 972e91c..44e8d47 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -3281,7 +3281,33 @@ void switch_mode(CPUARMState *env, int mode)
> */
> unsigned int arm_excp_target_el(CPUState *cs, unsigned int excp_idx)
> {
> - return 1;
> + CPUARMState *env = cs->env_ptr;
> + unsigned int cur_el = arm_current_pl(env);
> + unsigned int target_el = 1;
> + bool route_to_el2 = false;
> + /* FIXME: Use actual secure state. */
> + bool secure = false;
> +
> + if (!env->aarch64) {
> + /* TODO: Add EL2 and 3 exception handling for AArch32. */
> + return 1;
> + }
> +
> + if (!secure
> + && arm_feature(env, ARM_FEATURE_EL2)
> + && cur_el < 2
> + && (env->cp15.hcr_el2 & HCR_TGE)) {
> + route_to_el2 = true;
> + }
> +
> + target_el = MAX(cur_el, route_to_el2 ? 2 : 1);
> +
> + switch (excp_idx) {
> + case EXCP_HVC:
> + target_el = MAX(target_el, 2);
> + break;
> + }
> + return target_el;
I was wondering if this was going to get a bit heavyweight to
call twice on each trip round the cpu-exec.c main loop, but
we'll only do that in the case that an interrupt is pending
but currently masked I guess so it should be OK.
> }
>
> static void v7m_push(CPUARMState *env, uint32_t val)
> diff --git a/target-arm/helper.h b/target-arm/helper.h
> index facfcd2..70cfd28 100644
> --- a/target-arm/helper.h
> +++ b/target-arm/helper.h
> @@ -50,6 +50,7 @@ DEF_HELPER_2(exception_internal, void, env, i32)
> DEF_HELPER_3(exception_with_syndrome, void, env, i32, i32)
> DEF_HELPER_1(wfi, void, env)
> DEF_HELPER_1(wfe, void, env)
> +DEF_HELPER_2(hvc, void, env, i32)
>
> DEF_HELPER_3(cpsr_write, void, env, i32, i32)
> DEF_HELPER_1(cpsr_read, i32, env)
> diff --git a/target-arm/internals.h b/target-arm/internals.h
> index 08fa697..b68e6f9 100644
> --- a/target-arm/internals.h
> +++ b/target-arm/internals.h
> @@ -53,6 +53,7 @@ static const char * const excnames[] = {
> [EXCP_EXCEPTION_EXIT] = "QEMU v7M exception exit",
> [EXCP_KERNEL_TRAP] = "QEMU intercept of kernel commpage",
> [EXCP_STREX] = "QEMU intercept of STREX",
> + [EXCP_HVC] = "Hypervisor Call",
> };
>
> static inline void arm_log_exception(int idx)
> @@ -204,6 +205,11 @@ static inline uint32_t syn_aa64_svc(uint32_t imm16)
> return (EC_AA64_SVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | (imm16 & 0xffff);
> }
>
> +static inline uint32_t syn_aa64_hvc(uint16_t imm16)
This isn't consistent with the other syn_ functions which take a
uint32_t imm16. (Didn't we do this before?)
> +{
> + return (EC_AA64_HVC << ARM_EL_EC_SHIFT) | ARM_EL_IL | imm16;
> +}
> +
> static inline uint32_t syn_aa32_svc(uint32_t imm16, bool is_thumb)
> {
> return (EC_AA32_SVC << ARM_EL_EC_SHIFT) | (imm16 & 0xffff)
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index 25ad902..c1fa797 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -369,6 +369,39 @@ void HELPER(msr_i_pstate)(CPUARMState *env, uint32_t op,
> uint32_t imm)
> }
> }
>
> +void HELPER(hvc)(CPUARMState *env, uint32_t syndrome)
> +{
> + int cur_el = arm_current_pl(env);
> + /* FIXME: Use actual secure state. */
> + bool secure = false;
> + bool udef;
> +
> + /* We've already checked that EL2 exists at translation time.
> + * EL3.HCE has priority over EL2.HCD.
> + */
> + if (arm_feature(env, ARM_FEATURE_EL3)) {
> + udef = !(env->cp15.scr_el3 & SCR_HCE);
> + } else {
> + udef = env->cp15.hcr_el2 & HCR_HCD;
> + }
> +
> + /* In ARMv7 and ARMv8/AArch32, HVC is udef in secure state.
> + * For ARMv8/AArch64, HVC is allowed in EL3.
> + * Note that we've already trapped HVC from EL0 at translation
> + * time.
> + */
> + if (secure && (!is_a64(env) || cur_el == 1)) {
> + udef = true;
> + }
> +
> + if (udef) {
> + env->exception.syndrome = syn_uncategorized();
> + raise_exception(env, EXCP_UDEF);
> + }
> + env->exception.syndrome = syndrome;
> + raise_exception(env, EXCP_HVC);
> +}
> +
> void HELPER(exception_return)(CPUARMState *env)
> {
> int cur_el = arm_current_pl(env);
> diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
> index 63ad787..5692dff 100644
> --- a/target-arm/translate-a64.c
> +++ b/target-arm/translate-a64.c
> @@ -1436,17 +1436,28 @@ static void disas_exc(DisasContext *s, uint32_t insn)
> int opc = extract32(insn, 21, 3);
> int op2_ll = extract32(insn, 0, 5);
> int imm16 = extract32(insn, 5, 16);
> + TCGv_i32 tmp;
>
> switch (opc) {
> case 0:
> - /* SVC, HVC, SMC; since we don't support the Virtualization
> - * or TrustZone extensions these all UNDEF except SVC.
> - */
> - if (op2_ll != 1) {
> + switch (op2_ll) {
> + case 1:
> + gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
> + break;
> + case 2:
> + if (!arm_dc_feature(s, ARM_FEATURE_EL2) || s->current_pl == 0) {
> + unallocated_encoding(s);
> + break;
> + }
> + tmp = tcg_const_i32(syn_aa64_hvc(imm16));
> + gen_a64_set_pc_im(s->pc);
(This set_pc_im is unnecessary.)
> + gen_helper_hvc(cpu_env, tmp);
This means that exceptions due to HVC are going to be
runtime-detected and cause us to go through and retranslate
the TB to determine the guest PC. Maybe we should do:
/* This helper will raise EXCP_UDEF if HVC is not permitted */
gen_helper_hvc_access_check(cpu_env);
/* Common case: HVC causes EXCP_HVC */
gen_exception_insn(s, 0, EXCP_HVC, syn_aa64_hvc(imm16));
Then you only get the overhead of retranslating the TB in the
unexpected case where the guest does something dumb and
executes an HVC that UNDEFs.
> + tcg_temp_free_i32(tmp);
> + break;
> + default:
> unallocated_encoding(s);
> break;
> }
> - gen_exception_insn(s, 0, EXCP_SWI, syn_aa64_svc(imm16));
> break;
> case 1:
> if (op2_ll != 0) {
General comment, this is likely to clash with the PSCI support; I
guess we'll see which gets in first.
thanks
-- PMM
- Re: [Qemu-devel] [PATCH v3 13/16] target-arm: A64: Emulate the HVC insn,
Peter Maydell <=