On 2016年05月11日 20:27, Matt Fleming wrote: > On Fri, 06 May, at 04:32:06PM, Shannon Zhao wrote: >> > From: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >> > >> > Add a new function to parse DT parameters for Xen specific UEFI just >> > like the way for normal UEFI. Then it could reuse the existing codes. >> > >> > If Xen supports EFI, initialize runtime services. > > This commit log would benefit from a little expansion. I'd like to see > information that answers the following questions, > > - How do the Xen DT paramters differ from bare metal? > - What existing code is reused with your patch? > - How are Xen runtime services different from bare metal? > - Why is it OK to force enable EFI runtime services for Xen? > > I think it would also be good to explicitly state that we do not > expect to find both Xen EFI DT parameters and bare metal EFI DT > parameters when performing the search; the two should be mutually > exclusive. > >> > CC: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> >> > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >> > --- >> > Drop using of EFI_PARAVIRT. Discussion can be found from [1]. >> > [1] https://lkml.org/lkml/2016/4/29/8 >> > --- >> > arch/arm/include/asm/efi.h | 2 + >> > arch/arm/xen/enlighten.c | 16 ++++++++ >> > arch/arm64/include/asm/efi.h | 2 + >> > drivers/firmware/efi/arm-runtime.c | 70 +++++++++++++++++++++++--------- >> > drivers/firmware/efi/efi.c | 81 ++++++++++++++++++++++++++++++-------- >> > 5 files changed, 137 insertions(+), 34 deletions(-) >> > >> > diff --git a/arch/arm/include/asm/efi.h b/arch/arm/include/asm/efi.h >> > index e0eea72..5ba4343 100644 >> > --- a/arch/arm/include/asm/efi.h >> > +++ b/arch/arm/include/asm/efi.h >> > @@ -52,9 +52,11 @@ static inline void efi_set_pgd(struct mm_struct *mm) >> > >> > void efi_virtmap_load(void); >> > void efi_virtmap_unload(void); >> > +int xen_arm_enable_runtime_services(void); >> > >> > #else >> > #define efi_init() >> > +#define xen_arm_enable_runtime_services() (0) >> > #endif /* CONFIG_EFI */ >> > >> > /* arch specific definitions used by the stub code */ >> > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c >> > index 13e3e9f..3362870 100644 >> > --- a/arch/arm/xen/enlighten.c >> > +++ b/arch/arm/xen/enlighten.c >> > @@ -16,6 +16,7 @@ >> > #include <asm/xen/hypervisor.h> >> > #include <asm/xen/hypercall.h> >> > #include <asm/system_misc.h> >> > +#include <asm/efi.h> >> > #include <linux/interrupt.h> >> > #include <linux/irqreturn.h> >> > #include <linux/module.h> >> > @@ -261,6 +262,13 @@ static int __init fdt_find_hyper_node(unsigned long node, const char *uname, >> > !strncmp(hyper_node.prefix, s, strlen(hyper_node.prefix))) >> > hyper_node.version = s + strlen(hyper_node.prefix); >> > >> > + if (IS_ENABLED(CONFIG_XEN_EFI)) { >> > + /* Check if Xen supports EFI */ >> > + if ((of_get_flat_dt_subnode_by_name(node, "uefi") > 0) && >> > + !efi_runtime_disabled()) >> > + set_bit(EFI_RUNTIME_SERVICES, &efi.flags); >> > + } >> > + >> > return 0; >> > } >> > > The above comment could do with including similar information to the > commit log as to why we want to force enable runtime services. For x86 > we have this, > > * > * When EFI_PARAVIRT is in force then we could not map runtime > * service memory region because we do not have direct access to it. > * However, runtime services are available through proxy functions > * (e.g. in case of Xen dom0 EFI implementation they call special > * hypercall which executes relevant EFI functions) and that is why > * they are always enabled. > */ > > We need something similar here. > >> > @@ -338,6 +346,7 @@ static int __init xen_guest_init(void) >> > { >> > struct xen_add_to_physmap xatp; >> > struct shared_info *shared_info_page = NULL; >> > + int ret; >> > >> > if (!xen_domain()) >> > return 0; >> > @@ -352,6 +361,13 @@ static int __init xen_guest_init(void) >> > return -ENODEV; >> > } >> > >> > + if (IS_ENABLED(CONFIG_XEN_EFI) && efi_enabled(EFI_BOOT) && >> > + efi_enabled(EFI_RUNTIME_SERVICES)) { >> > + ret = xen_arm_enable_runtime_services(); >> > + if (ret) >> > + return ret; >> > + } >> > + > Is it ever possible to have EFI_RUNTIME_SERVICES set but > efi_enabled(EFI_BOOT) and IS_ENABLED(CONFIG_XEN_EFI) be false inside > this function? If the answer is "no", I'd suggest just reducing this > down to, > > /* > * The fdt parsing code will have set EFI_RUNTIME_SERVICES if > * it found Xen EFI parameters. Force enable runtime services. > */ > if (efi_enabled(EFI_RUNTIME_SERVICES)) { > ret = xen_arm_enable_runtime_services(); > if (ret) > return ret; > } > > But first, see my comments below. > >> > @@ -39,6 +40,33 @@ static struct mm_struct efi_mm = { >> > .mmlist = LIST_HEAD_INIT(efi_mm.mmlist), >> > }; >> > >> > +static int __init efi_remap_init(void) >> > +{ >> > + u64 mapsize; >> > + >> > + pr_info("Remapping and enabling EFI services.\n"); >> > + >> > + mapsize = memmap.map_end - memmap.map; >> > + memmap.map = (__force void *)ioremap_cache(memmap.phys_map, >> > + mapsize); >> > + if (!memmap.map) { >> > + pr_err("Failed to remap EFI memory map\n"); >> > + return -ENOMEM; >> > + } >> > + memmap.map_end = memmap.map + mapsize; >> > + efi.memmap = &memmap; >> > + >> > + efi.systab = (__force void *)ioremap_cache(efi_system_table, >> > + sizeof(efi_system_table_t)); >> > + if (!efi.systab) { >> > + pr_err("Failed to remap EFI System Table\n"); >> > + return -ENOMEM; >> > + } >> > + set_bit(EFI_SYSTEM_TABLES, &efi.flags); >> > + >> > + return 0; >> > +} >> > + >> > static bool __init efi_virtmap_init(void) >> > { >> > efi_memory_desc_t *md; >> > @@ -75,7 +103,7 @@ static bool __init efi_virtmap_init(void) >> > */ >> > static int __init arm_enable_runtime_services(void) >> > { >> > - u64 mapsize; >> > + int ret; >> > >> > if (!efi_enabled(EFI_BOOT)) { >> > pr_info("EFI services will not be available.\n"); >> > @@ -87,25 +115,14 @@ static int __init arm_enable_runtime_services(void) >> > return 0; >> > } >> > >> > - pr_info("Remapping and enabling EFI services.\n"); >> > - >> > - mapsize = memmap.map_end - memmap.map; >> > - memmap.map = (__force void *)ioremap_cache(memmap.phys_map, >> > - mapsize); >> > - if (!memmap.map) { >> > - pr_err("Failed to remap EFI memory map\n"); >> > - return -ENOMEM; >> > + if (efi_enabled(EFI_RUNTIME_SERVICES)) { >> > + pr_info("EFI runtime services access via paravirt.\n"); >> > + return 0; >> > } >> > - memmap.map_end = memmap.map + mapsize; >> > - efi.memmap = &memmap; >> > >> > - efi.systab = (__force void *)ioremap_cache(efi_system_table, >> > - sizeof(efi_system_table_t)); >> > - if (!efi.systab) { >> > - pr_err("Failed to remap EFI System Table\n"); >> > - return -ENOMEM; >> > - } >> > - set_bit(EFI_SYSTEM_TABLES, &efi.flags); >> > + ret = efi_remap_init(); >> > + if (ret) >> > + return ret; >> > >> > if (!efi_virtmap_init()) { >> > pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n"); >> > @@ -122,6 +139,23 @@ static int __init arm_enable_runtime_services(void) >> > } >> > early_initcall(arm_enable_runtime_services); >> > >> > +int __init xen_arm_enable_runtime_services(void) >> > +{ >> > + int ret; >> > + >> > + ret = efi_remap_init(); >> > + if (ret) >> > + return ret; >> > + >> > + if (IS_ENABLED(CONFIG_XEN_EFI)) { >> > + /* Set up runtime services function pointers for Xen Dom0 */ >> > + xen_efi_runtime_setup(); >> > + efi.runtime_version = efi.systab->hdr.revision; >> > + } >> > + >> > + return 0; >> > +} > Since you call efi_remap_init() in both of these functions, couldn't > you leave the existing code alone and bail after setting up the memory > map and systab in arm_enable_runtime_services()? > > Also, why do you need to setup efi.runtime_version here? Isn't that > done inside uefi_init()? > I don't see any codes which setup efi.runtime_version in uefi_init(). > Here is how I would have expected this patch to look: > > - Add FDT code to find hypervisor EFI params > > - Force enable EFI_RUNTIME_SERVICES for Xen and call > xen_efi_runtime_setup() inside xen_guest_init() > > - Change arm_enable_runtime_services() to handle the case where > EFI_RUNTIME_SERVICES is already set > > Am I misunderstanding some ordering issues? Since xen_guest_init() and arm_enable_runtime_services() are both early_initcall and the calling order is random I think. And when we call xen_efi_runtime_setup() and setup efi.runtime_version in xen_guest_init(), the efi.systab might be NULL. So it needs to map the systanle explicitly before we use efi.systab. Thanks, -- Shannon -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
