| Message ID | 20250226112625.2217195-1-luca.fancellu@arm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] xen/arm: Don't use copy_from_paddr for DTB relocation | expand |
On 26/02/2025 12:26, Luca Fancellu wrote: > > > Currently the early stage of the Arm boot maps the DTB using > early_fdt_map() using PAGE_HYPERVISOR_RO which is cacheable > read-only memory, later during DTB relocation the function > copy_from_paddr() is used to map pages in the same range on > the fixmap but using PAGE_HYPERVISOR_WC which is non-cacheable > read-write memory. > > The Arm specifications, ARM DDI0487L.a, section B2.11 "Mismatched > memory attributes" discourage using mismatched attributes for > aliases of the same location. > > Given that there is nothing preventing the relocation since the region > is already mapped, fix that by open-coding copy_from_paddr inside > relocate_fdt, without mapping on the fixmap. > > Signed-off-by: Luca Fancellu <luca.fancellu@arm.com> Acked-by: Michal Orzel <michal.orzel@amd.com> ~Michal
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c index c1f2d1b89d43..2a9747a50abc 100644 --- a/xen/arch/arm/setup.c +++ b/xen/arch/arm/setup.c @@ -237,16 +237,17 @@ void __init discard_initial_modules(void) } /* Relocate the FDT in Xen heap */ -static void * __init relocate_fdt(paddr_t dtb_paddr, size_t dtb_size) +static void __init relocate_fdt(const void *dtb_vaddr, size_t dtb_size) { void *fdt = xmalloc_bytes(dtb_size); if ( !fdt ) panic("Unable to allocate memory for relocating the Device-Tree.\n"); - copy_from_paddr(fdt, dtb_paddr, dtb_size); + memcpy(fdt, dtb_vaddr, dtb_size); + clean_dcache_va_range(fdt, dtb_size); - return fdt; + dtb_vaddr = fdt; } void __init init_pdx(void) @@ -362,7 +363,7 @@ void asmlinkage __init start_xen(unsigned long fdt_paddr) if ( acpi_disabled ) { printk("Booting using Device Tree\n"); - device_tree_flattened = relocate_fdt(fdt_paddr, fdt_size); + relocate_fdt(device_tree_flattened, fdt_size); dt_unflatten_host_device_tree(); } else
Currently the early stage of the Arm boot maps the DTB using early_fdt_map() using PAGE_HYPERVISOR_RO which is cacheable read-only memory, later during DTB relocation the function copy_from_paddr() is used to map pages in the same range on the fixmap but using PAGE_HYPERVISOR_WC which is non-cacheable read-write memory. The Arm specifications, ARM DDI0487L.a, section B2.11 "Mismatched memory attributes" discourage using mismatched attributes for aliases of the same location. Given that there is nothing preventing the relocation since the region is already mapped, fix that by open-coding copy_from_paddr inside relocate_fdt, without mapping on the fixmap. Signed-off-by: Luca Fancellu <luca.fancellu@arm.com> --- xen/arch/arm/setup.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)