Hi Julien, On 11/01/2024 19:34, Julien Grall wrote: > > > From: Julien Grall <[email protected]> > > Since commit 5e213f0f4d2c ("xen/arm32: head: Widen the use of the > temporary mapping"), boot_second (used to cover regions like Xen and > the fixmap) will not be mapped if the identity mapping overlap. > > So it is ok to prepare the fixmap table and link it in boot_second > earlier. With that, the fixmap can also be used earlier via the > temporary mapping. > > Therefore split setup_fixmap() in two: > * The table is now linked in create_page_tables() because > the boot page tables needs to be recreated for every CPU. > * The early UART mapping is only added for the boot CPU0 as the > fixmap table is not cleared when secondary CPUs boot. > > Signed-off-by: Julien Grall <[email protected]> Reviewed-by: Michal Orzel <[email protected]>
with below 2 adjustments: > > ---- > > Changelog since v1: > * Rebase > * Move the UART mapping enable_mm_boot_cpu() > --- > xen/arch/arm/arm32/mmu/head.S | 61 ++++++++--------------------------- > 1 file changed, 14 insertions(+), 47 deletions(-) > > diff --git a/xen/arch/arm/arm32/mmu/head.S b/xen/arch/arm/arm32/mmu/head.S > index 4e6395e7876d..a90799ad5451 100644 > --- a/xen/arch/arm/arm32/mmu/head.S > +++ b/xen/arch/arm/arm32/mmu/head.S > @@ -165,11 +165,6 @@ > * Rebuild the boot pagetable's first-level entries. The structure > * is described in mm.c. > * > - * After the CPU enables paging it will add the fixmap mapping > - * to these page tables, however this may clash with the 1:1 > - * mapping. So each CPU must rebuild the page tables here with > - * the 1:1 in place. > - * > * Inputs: > * r9 : paddr(start) > * r10: phys offset > @@ -197,6 +192,10 @@ create_page_tables: > add r5, r5, #PAGE_SIZE /* r5 := Next table */ > .endr > > + /* Map the fixmap into boot_second */ > + mov_w r0, FIXMAP_ADDR(0) > + create_table_entry boot_second, xen_fixmap, r0, 2 > + > /* > * Find the size of Xen in pages and multiply by the size of a > * PTE. This will then be compared in the mapping loop below. > @@ -442,19 +441,20 @@ ENDPROC(enable_secondary_cpu_mm) > ENTRY(enable_boot_cpu_mm) > mov r6, lr > > +#ifdef CONFIG_EARLY_PRINTK > + /* > + * Add the UART mapping to the fixmap so the UART can be used > + * as the MMU is on. This only need to do done on the boot CPU. s/need to do done/needs to be done/ > + */ > + mov_w r0, EARLY_UART_VIRTUAL_ADDRESS > + create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 Would you mind listing r11 in the Input section of a comment? ~Michal
