Re: [PATCH 1/2] arm64: dts: meson: fix reserve memory regions

[Mark Rutland]

On Mon, Oct 15, 2018 at 06:28:32PM +0200, Jerome Brunet wrote:
> Since commit 50d7ba36b916 ("arm64: export memblock_reserve()d regions via /proc/iomem")
> was merged Amlogic's boards using mainline u-boot started showing the
> following warning:
>
> WARNING: CPU: 0 PID: 1 at arch/arm64/kernel/setup.c:271 reserve_memblock_reserved_regions+0xd8/0x144
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc7-00263-g385684b3eb27-dirty #254
> pstate: 40000005 (nZcv daif -PAN -UAO)
> pc : reserve_memblock_reserved_regions+0xd8/0x144
> lr : reserve_memblock_reserved_regions+0xd0/0x144
> [...]
>
> This is due to u-boot setting some /reservedmem/ region while our
> dts declares reserved memory on the same region with no-map.
>
> The conflict produce the warning. This is fixed by using /reservedmem/
> in our dts as well, which is probably something we should have done from
> the beginning.

A /memreserve/ does not ensure no-map, and the kernel will map regions
which are described in a memory node and only protected with a
/memreserve/ entry.

Is it safe for the kernel to map these? e.g. speculative fetches won't
trigger a TrustZone controller to reboot the system?

... or are they not in memory nodes to begin with?

Thanks,
Mark.

>
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> ---
>
> Hi Kevin,
>
> I would have liked to put a Fixes tag above but I could not figure out
> which commit to pick, considering how much we changed those regions in
> the past. If you have suggestion, I'll be happy to repost this patch.
> If you prefer, feel free to amend this patch directly.
>
> Cheers
> Jerome
>
>  arch/arm64/boot/dts/amlogic/meson-axg.dtsi | 24 +++++--------------
>  arch/arm64/boot/dts/amlogic/meson-gx.dtsi  | 27 ++++++++--------------
>  2 files changed, 15 insertions(+), 36 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> index 178d8e8c56b8..06a06f11f114 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-axg.dtsi
> @@ -13,6 +13,12 @@
>  #include <dt-bindings/reset/amlogic,meson-axg-audio-arb.h>
>  #include <dt-bindings/reset/amlogic,meson-axg-reset.h>
>
> +/* 16 MiB reserved for Hardware ROM Firmware */
> +/memreserve/ 0x0 0x1000000;
> +
> +/* 3 MiB reserved for ARM Trusted Firmware (BL31) */
> +/memreserve/ 0x05000000 0x300000;
> +
>  / {
>       compatible = "amlogic,meson-axg";
>
> @@ -115,24 +121,6 @@
>               method = "smc";
>       };
>
> -     reserved-memory {
> -             #address-cells = <2>;
> -             #size-cells = <2>;
> -             ranges;
> -
> -             /* 16 MiB reserved for Hardware ROM Firmware */
> -             hwrom_reserved: hwrom@0 {
> -                     reg = <0x0 0x0 0x0 0x1000000>;
> -                     no-map;
> -             };
> -
> -             /* Alternate 3 MiB reserved for ARM Trusted Firmware (BL31) */
> -             secmon_reserved: secmon@5000000 {
> -                     reg = <0x0 0x05000000 0x0 0x300000>;
> -                     no-map;
> -             };
> -     };
> -
>       soc {
>               compatible = "simple-bus";
>               #address-cells = <2>;
> diff --git a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
> index 676a995fb912..23e879b29b1e 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-gx.dtsi
> @@ -13,6 +13,15 @@
>  #include <dt-bindings/interrupt-controller/irq.h>
>  #include <dt-bindings/interrupt-controller/arm-gic.h>
>
> +/* 16 MiB reserved for Hardware ROM Firmware */
> +/memreserve/ 0x0 0x1000000;
> +
> +/* 2 MiB reserved for ARM Trusted Firmware (BL31) */
> +/memreserve/ 0x10000000 0x200000;
> +
> +/* Alternate 3 MiB reserved for ARM Trusted Firmware (BL31) */
> +/memreserve/ 0x05000000 0x300000;
> +
>  / {
>       interrupt-parent = <&gic>;
>       #address-cells = <2>;
> @@ -23,24 +32,6 @@
>               #size-cells = <2>;
>               ranges;
>
> -             /* 16 MiB reserved for Hardware ROM Firmware */
> -             hwrom_reserved: hwrom@0 {
> -                     reg = <0x0 0x0 0x0 0x1000000>;
> -                     no-map;
> -             };
> -
> -             /* 2 MiB reserved for ARM Trusted Firmware (BL31) */
> -             secmon_reserved: secmon@10000000 {
> -                     reg = <0x0 0x10000000 0x0 0x200000>;
> -                     no-map;
> -             };
> -
> -             /* Alternate 3 MiB reserved for ARM Trusted Firmware (BL31) */
> -             secmon_reserved_alt: secmon@5000000 {
> -                     reg = <0x0 0x05000000 0x0 0x300000>;
> -                     no-map;
> -             };
> -
>               linux,cma {
>                       compatible = "shared-dma-pool";
>                       reusable;
> --
> 2.17.2
>
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