target/arm: Implement emulation of nested virtualization

[PATCH 15/35] target/arm: Set SPSR_EL1.M correctly when nested virt is enabled

Posted by Peter Maydell 11 months, 2 weeks ago

FEAT_NV requires that when HCR_EL2.{NV,NV1} == {1,0} and an exception
is taken from EL1 to EL1 then the reported EL in SPSR_EL1.M should be
EL2, not EL1.  Implement this behaviour.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/helper.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 44005665d12..220ee64df0d 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11327,6 +11327,12 @@ static void arm_cpu_do_interrupt_aarch64(CPUState *cs)
         old_mode = pstate_read(env);
         aarch64_save_sp(env, arm_current_el(env));
         env->elr_el[new_el] = env->pc;
+
+        if (cur_el == 1 && new_el == 1 &&
+            ((arm_hcr_el2_eff(env) & (HCR_NV | HCR_NV1)) == HCR_NV)) {
+            /* I_ZJRNN: report EL2 in the SPSR by setting M[3:2] to 0b10 */
+            old_mode = deposit32(old_mode, 2, 2, 2);
+        }
     } else {
         old_mode = cpsr_read_for_spsr_elx(env);
         env->elr_el[new_el] = env->regs[15];
-- 
2.34.1

Re: [PATCH 15/35] target/arm: Set SPSR_EL1.M correctly when nested virt is enabled

Posted by Richard Henderson 11 months ago

On 12/18/23 22:32, Peter Maydell wrote:
> FEAT_NV requires that when HCR_EL2.{NV,NV1} == {1,0} and an exception
> is taken from EL1 to EL1 then the reported EL in SPSR_EL1.M should be
> EL2, not EL1.  Implement this behaviour.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   target/arm/helper.c | 6 ++++++
>   1 file changed, 6 insertions(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~