target/arm: Implement emulation of nested virtualization

[PATCH 14/35] target/arm: Make NV reads of CurrentEL return EL2

Posted by Peter Maydell 11 months, 2 weeks ago

FEAT_NV requires that when HCR_EL2.NV is set reads of the CurrentEL
register from EL1 always report EL2 rather than the real EL.
Implement this.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/tcg/translate-a64.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index d060e24356d..6bfc39d8ea7 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -2240,12 +2240,17 @@ static void handle_sys(DisasContext *s, bool isread,
         }
         return;
     case ARM_CP_CURRENTEL:
-        /* Reads as current EL value from pstate, which is
+    {
+        /*
+         * Reads as current EL value from pstate, which is
          * guaranteed to be constant by the tb flags.
+         * For nested virt we should report EL2.
          */
+        int el = s->nv ? 2 : s->current_el;
         tcg_rt = cpu_reg(s, rt);
-        tcg_gen_movi_i64(tcg_rt, s->current_el << 2);
+        tcg_gen_movi_i64(tcg_rt, el << 2);
         return;
+    }
     case ARM_CP_DC_ZVA:
         /* Writes clear the aligned block of memory which rt points into. */
         if (s->mte_active[0]) {
-- 
2.34.1

Re: [PATCH 14/35] target/arm: Make NV reads of CurrentEL return EL2

Posted by Richard Henderson 11 months ago

On 12/18/23 22:32, Peter Maydell wrote:
> FEAT_NV requires that when HCR_EL2.NV is set reads of the CurrentEL
> register from EL1 always report EL2 rather than the real EL.
> Implement this.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   target/arm/tcg/translate-a64.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)

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

r~