Re: [PATCH v3 18/26] hw/arm/boot: Mark all guest memory as RIPAS_RAM.

[Gavin Shan]

On 11/26/24 5:56 AM, Jean-Philippe Brucker wrote:
> All Realm IPA states are by default RIPAS_EMPTY, and accessing them in
> that state causes injection of synchronous exception. Either the loader
> or the guest needs to set IPA state to RIPAS_RAM before accessing it.
> Since a Linux guest needs all memory ready at boot [1], initialize it
> here.
>
> [1] https://docs.kernel.org/arch/arm64/booting.html
>      https://lore.kernel.org/all/20241004144307.66199-12-steven.price@arm.com/
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
> v2->v3: New: the Linux guest does not initialize RIPAS itself anymore,
> and expects the loader to do it.
> ---
>   hw/arm/boot.c | 4 ++++
>   1 file changed, 4 insertions(+)

I think the changes in this patch can be combined to the following one,
or move this after it. It logically to initialize guest's RAM covered
by PATCH[9]. I'm not sure if there is particular reasonable why we
don't do that.

PATCH[09/26] target/arm/kvm-rme: Initialize Realm memory

> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index 5301d8d318..a2414b1f98 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -26,6 +26,7 @@
>   #include "qemu/config-file.h"
>   #include "qemu/option.h"
>   #include "qemu/units.h"
> +#include "kvm_arm.h"
>   
>   /* Kernel boot protocol is specified in the kernel docs
>    * Documentation/arm/Booting and Documentation/arm64/booting.txt
> @@ -1238,6 +1239,9 @@ void arm_load_kernel(ARMCPU *cpu, MachineState *ms, 
> struct arm_boot_info *info)
>       info->dtb_filename = ms->dtb;
>       info->dtb_limit = 0;
>   
> +    /* Mark all Realm memory as RAM */
> +    kvm_arm_rme_init_guest_ram(info->loader_start, info->ram_size);
> +
>       /* Load the kernel.  */
>       if (!info->kernel_filename || info->firmware_loaded) {
>           arm_setup_firmware_boot(cpu, info);

Thanks,
Gavin