Re: [PATCH v4 5/6] hw/arm/virt: Disable highmem devices that don't fit in the PA range

[Eric Auger]

Hi Marc,

On 1/7/22 5:33 PM, Marc Zyngier wrote:
> In order to only keep the highmem devices that actually fit in
> the PA range, check their location against the range and update
> highest_gpa if they fit. If they don't, mark them them as disabled.
s/them them/them
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  hw/arm/virt.c | 34 ++++++++++++++++++++++++++++------
>  1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index db4b0636e1..70b4773b3e 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1711,21 +1711,43 @@ static void virt_set_memmap(VirtMachineState *vms, 
> int pa_bits)
>          base = vms->memmap[VIRT_MEM].base + LEGACY_RAMLIMIT_BYTES;
>      }
>  
> +    /* We know for sure that at least the memory fits in the PA space */
> +    vms->highest_gpa = memtop - 1;
> +
>      for (i = VIRT_LOWMEMMAP_LAST; i < ARRAY_SIZE(extended_memmap); i++) {
>          hwaddr size = extended_memmap[i].size;
> +        bool fits;
>  
>          base = ROUND_UP(base, size);
>          vms->memmap[i].base = base;
>          vms->memmap[i].size = size;
> +
> +        /*
> +         * Check each device to see if they fit in the PA space,
> +         * moving highest_gpa as we go.
> +         *
> +         * For each device that doesn't fit, disable it.
> +         */
> +        fits = (base + size) <= BIT_ULL(pa_bits);
> +        if (fits) {
> +            vms->highest_gpa = MAX(vms->highest_gpa, base + size - 1);
why do you need the MAX()?
> +        }
> +        switch (i) {
> +        case VIRT_HIGH_GIC_REDIST2:
> +            vms->highmem_redists &= fits;
> +            break;
> +        case VIRT_HIGH_PCIE_ECAM:
> +            vms->highmem_ecam &= fits;
> +            break;
> +        case VIRT_HIGH_PCIE_MMIO:
> +            vms->highmem_mmio &= fits;
> +            break;
> +        }
> +
>          base += size;
>      }
>  
> -    /*
> -     * If base fits within pa_bits, all good. If it doesn't, limit it
> -     * to the end of RAM, which is guaranteed to fit within pa_bits.
> -     */
> -    vms->highest_gpa = (base <= BIT_ULL(pa_bits) ? base : memtop) - 1;
> -
>      if (device_memory_size > 0) {
>          ms->device_memory = g_malloc0(sizeof(*ms->device_memory));
>          ms->device_memory->base = device_memory_base;
Eric