target/arm: Make '-cpu max' have a 48-bit PA

[PATCH] target/arm: Make '-cpu max' have a 48-bit PA

Peter Maydell posted 1 patch 3 years, 7 months ago

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git fetch https://github.com/patchew-project/qemu tags/patchew/20201001160116.18095-1-peter.maydell@linaro.org

Maintainers: Peter Maydell <peter.maydell@linaro.org>

target/arm/cpu64.c | 4 ++++
1 file changed, 4 insertions(+)

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[PATCH] target/arm: Make '-cpu max' have a 48-bit PA

Posted by Peter Maydell 3 years, 7 months ago

QEMU supports a 48-bit physical address range, but we don't currently
expose it in the '-cpu max' ID registers (you get the same range as
Cortex-A57, which is 44 bits).

Set the ID_AA64MMFR0.PARange field to indicate 48 bits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
I forget why I wanted this patch originally, it's been so long
since I wrote it, but it seems like a useful thing to allow -cpu max
to have a big PA range...
---
 target/arm/cpu64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index 3c2b3d95993..3ba7f1675cc 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -653,6 +653,10 @@ static void aarch64_max_initfn(Object *obj)
         t = FIELD_DP64(t, ID_AA64PFR1, MTE, 2);
         cpu->isar.id_aa64pfr1 = t;
 
+        t = cpu->isar.id_aa64mmfr0;
+        t = FIELD_DP64(t, ID_AA64MMFR0, PARANGE, 5); /* PARange: 48 bits */
+        cpu->isar.id_aa64mmfr0 = t;
+
         t = cpu->isar.id_aa64mmfr1;
         t = FIELD_DP64(t, ID_AA64MMFR1, HPDS, 1); /* HPD */
         t = FIELD_DP64(t, ID_AA64MMFR1, LO, 1);
-- 
2.20.1

Re: [PATCH] target/arm: Make '-cpu max' have a 48-bit PA

Posted by Richard Henderson 3 years, 7 months ago

On 10/1/20 11:01 AM, Peter Maydell wrote:
> QEMU supports a 48-bit physical address range, but we don't currently
> expose it in the '-cpu max' ID registers (you get the same range as
> Cortex-A57, which is 44 bits).
> 
> Set the ID_AA64MMFR0.PARange field to indicate 48 bits.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I forget why I wanted this patch originally, it's been so long
> since I wrote it, but it seems like a useful thing to allow -cpu max
> to have a big PA range...
> ---
>  target/arm/cpu64.c | 4 ++++
>  1 file changed, 4 insertions(+)

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

Were you by chance looking at some of the optional v8.2 extensions, one of
which is a 52-bit VA, and noticed this nit?


r~