Re: [PATCH 1/4] xen/acpi: Rework acpi_os_map_memory() and acpi_os_unmap_memory()

[Rahul Singh <Rahul.Singh@arm.com>]

Hello,

> On 26 Sep 2020, at 9:55 pm, Julien Grall <julien@xen.org> wrote:
> 
> From: Julien Grall <jgrall@amazon.com>
> 
> The functions acpi_os_{un,}map_memory() are meant to be arch-agnostic
> while the __acpi_os_{un,}map_memory() are meant to be arch-specific.
> 
> Currently, the former are still containing x86 specific code.
> 
> To avoid this rather strange split, the generic helpers are reworked so
> they are arch-agnostic. This requires the introduction of a new helper
> __acpi_os_unmap_memory() that will undo any mapping done by
> __acpi_os_map_memory().
> 
> Currently, the arch-helper for unmap is basically a no-op so it only
> returns whether the mapping was arch specific. But this will change
> in the future.
> 
> Note that the x86 version of acpi_os_map_memory() was already able to
> able the 1MB region. Hence why there is no addition of new code.
> 
> Signed-off-by: Julien Grall <jgrall@amazon.com>

Reviewed-by: Rahul Singh <rahul.singh@arm.com>
Tested-by: Rahul Singh <rahul.singh@arm.com>
> ---
> xen/arch/arm/acpi/lib.c | 10 ++++++++++
> xen/arch/x86/acpi/lib.c | 18 ++++++++++++++++++
> xen/drivers/acpi/osl.c  | 34 ++++++++++++++++++----------------
> xen/include/xen/acpi.h  |  1 +
> 4 files changed, 47 insertions(+), 16 deletions(-)
> 
> diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c
> index 4fc6e17322c1..2192a5519171 100644
> --- a/xen/arch/arm/acpi/lib.c
> +++ b/xen/arch/arm/acpi/lib.c
> @@ -30,6 +30,10 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
>     unsigned long base, offset, mapped_size;
>     int idx;
> 
> +    /* No arch specific implementation after early boot */
> +    if ( system_state >= SYS_STATE_boot )
> +        return NULL;
> +
>     offset = phys & (PAGE_SIZE - 1);
>     mapped_size = PAGE_SIZE - offset;
>     set_fixmap(FIXMAP_ACPI_BEGIN, maddr_to_mfn(phys), PAGE_HYPERVISOR);
> @@ -49,6 +53,12 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
>     return ((char *) base + offset);
> }
> 
> +bool __acpi_unmap_table(void *ptr, unsigned long size)
> +{
> +    return ( vaddr >= FIXMAP_ADDR(FIXMAP_ACPI_BEGIN) &&
> +             vaddr < (FIXMAP_ADDR(FIXMAP_ACPI_END) + PAGE_SIZE) );
> +}
> +
> /* True to indicate PSCI 0.2+ is implemented */
> bool __init acpi_psci_present(void)
> {
> diff --git a/xen/arch/x86/acpi/lib.c b/xen/arch/x86/acpi/lib.c
> index 265b9ad81905..77803f4d4c63 100644
> --- a/xen/arch/x86/acpi/lib.c
> +++ b/xen/arch/x86/acpi/lib.c
> @@ -46,6 +46,10 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
> 	if ((phys + size) <= (1 * 1024 * 1024))
> 		return __va(phys);
> 
> +	/* No arch specific implementation after early boot */
> +	if (system_state >= SYS_STATE_boot)
> +		return NULL;
> +
> 	offset = phys & (PAGE_SIZE - 1);
> 	mapped_size = PAGE_SIZE - offset;
> 	set_fixmap(FIX_ACPI_END, phys);
> @@ -66,6 +70,20 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
> 	return ((char *) base + offset);
> }
> 
> +bool __acpi_unmap_table(void *ptr, unsigned long size)
> +{
> +	unsigned long vaddr = (unsigned long)ptr;
> +
> +	if (vaddr >= DIRECTMAP_VIRT_START &&
> +	    vaddr < DIRECTMAP_VIRT_END) {
> +		ASSERT(!((__pa(ptr) + size - 1) >> 20));
> +		return true;
> +	}
> +
> +	return (vaddr >= __fix_to_virt(FIX_ACPI_END)) &&
> +		(vaddr < (__fix_to_virt(FIX_ACPI_BEGIN) + PAGE_SIZE));
> +}
> +
> unsigned int acpi_get_processor_id(unsigned int cpu)
> {
> 	unsigned int acpiid, apicid;
> diff --git a/xen/drivers/acpi/osl.c b/xen/drivers/acpi/osl.c
> index 4c8bb7839eda..100eee72def2 100644
> --- a/xen/drivers/acpi/osl.c
> +++ b/xen/drivers/acpi/osl.c
> @@ -92,27 +92,29 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
> void __iomem *
> acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
> {
> -	if (system_state >= SYS_STATE_boot) {
> -		mfn_t mfn = _mfn(PFN_DOWN(phys));
> -		unsigned int offs = phys & (PAGE_SIZE - 1);
> -
> -		/* The low first Mb is always mapped on x86. */
> -		if (IS_ENABLED(CONFIG_X86) && !((phys + size - 1) >> 20))
> -			return __va(phys);
> -		return __vmap(&mfn, PFN_UP(offs + size), 1, 1,
> -			      ACPI_MAP_MEM_ATTR, VMAP_DEFAULT) + offs;
> -	}
> -	return __acpi_map_table(phys, size);
> +	void *ptr;
> +	mfn_t mfn = _mfn(PFN_DOWN(phys));
> +	unsigned int offs = phys & (PAGE_SIZE - 1);
> +
> +	/* Try the arch specific implementation first */
> +	ptr = __acpi_map_table(phys, size);
> +	if (ptr)
> +		return ptr;
> +
> +	/* No common implementation for early boot map */
> +	if (unlikely(system_state < SYS_STATE_boot))
> +	     return NULL;
> +
> +	ptr = __vmap(&mfn, PFN_UP(offs + size), 1, 1,
> +		     ACPI_MAP_MEM_ATTR, VMAP_DEFAULT);
> +
> +	return !ptr ? NULL : (ptr + offs);
> }
> 
> void acpi_os_unmap_memory(void __iomem * virt, acpi_size size)
> {
> -	if (IS_ENABLED(CONFIG_X86) &&
> -	    (unsigned long)virt >= DIRECTMAP_VIRT_START &&
> -	    (unsigned long)virt < DIRECTMAP_VIRT_END) {
> -		ASSERT(!((__pa(virt) + size - 1) >> 20));
> +	if (__acpi_unmap_table(virt, size))
> 		return;
> -	}
> 
> 	if (system_state >= SYS_STATE_boot)
> 		vunmap((void *)((unsigned long)virt & PAGE_MASK));
> diff --git a/xen/include/xen/acpi.h b/xen/include/xen/acpi.h
> index c945ab05c864..5a84a4bf54e0 100644
> --- a/xen/include/xen/acpi.h
> +++ b/xen/include/xen/acpi.h
> @@ -68,6 +68,7 @@ typedef int (*acpi_table_entry_handler) (struct acpi_subtable_header *header, co
> 
> unsigned int acpi_get_processor_id (unsigned int cpu);
> char * __acpi_map_table (paddr_t phys_addr, unsigned long size);
> +bool __acpi_unmap_table(void *ptr, unsigned long size);
> int acpi_boot_init (void);
> int acpi_boot_table_init (void);
> int acpi_numa_init (void);
> -- 
> 2.17.1
> 
> 

Regards,
Rahul