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Re: [Xen-devel] [PATCH v5 4/7] xen: Put EFI machinery in place



On Fri, 13 Jun 2014, Daniel Kiper wrote:
> This patch enables EFI usage under Xen dom0. Standard EFI Linux
> Kernel infrastructure cannot be used because it requires direct
> access to EFI data and code. However, in dom0 case it is not possible
> because above mentioned EFI stuff is fully owned and controlled
> by Xen hypervisor. In this case all calls from dom0 to EFI must
> be requested via special hypercall which in turn executes relevant
> EFI code in behalf of dom0.
> 
> When dom0 kernel boots it checks for EFI availability on a machine.
> If it is detected then artificial EFI system table is filled.
> Native EFI callas are replaced by functions which mimics them
> by calling relevant hypercall. Later pointer to EFI system table
> is passed to standard EFI machinery and it continues EFI subsystem
> initialization taking into account that there is no direct access
> to EFI boot services, runtime, tables, structures, etc. After that
> system runs as usual.
> 
> This patch is based on Jan Beulich and Tang Liang work.
> 
> v5 - suggestions/fixes:
>    - improve macro usage readability
>      (suggested by Andrew Cooper and David Vrabel),
>    - conditions cleanup
>      (suggested by David Vrabel),
>    - use -fshort-wchar option
>      (suggested by Jan Beulich),
>    - Kconfig rule cleanup
>      (suggested by Jan Beulich),
>    - forward port fixes from SUSE kernel
>      (suggested by Jan Beulich),
>    - improve commit message
>      (suggested by David Vrabel).
> 
> v4 - suggestions/fixes:
>    - "just populate an efi_system_table_t object"
>      (suggested by Matt Fleming).
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Signed-off-by: Tang Liang <liang.tang@xxxxxxxxxx>
> Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>

Sorry for commenting on your patches so late in the review cycle.


>  arch/x86/xen/enlighten.c |   24 +++
>  drivers/xen/Kconfig      |    4 +
>  drivers/xen/Makefile     |    3 +
>  drivers/xen/efi.c        |  374 
> ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 405 insertions(+)
>  create mode 100644 drivers/xen/efi.c
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index f17b292..5dad11c 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -32,6 +32,7 @@
>  #include <linux/gfp.h>
>  #include <linux/memblock.h>
>  #include <linux/edd.h>
> +#include <linux/efi.h>
>  
>  #include <xen/xen.h>
>  #include <xen/events.h>
> @@ -150,6 +151,15 @@ struct shared_info *HYPERVISOR_shared_info = 
> &xen_dummy_shared_info;
>   */
>  static int have_vcpu_info_placement = 1;
>  
> +#ifdef CONFIG_XEN_EFI
> +extern efi_system_table_t __init *xen_efi_probe(void);
> +#else
> +static efi_system_table_t __init *xen_efi_probe(void)
> +{
> +     return NULL;
> +}
> +#endif
> +
>  struct tls_descs {
>       struct desc_struct desc[3];
>  };
> @@ -1520,6 +1530,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
>  {
>       struct physdev_set_iopl set_iopl;
>       int rc;
> +     efi_system_table_t *efi_systab_xen;
>  
>       if (!xen_start_info)
>               return;
> @@ -1715,6 +1726,19 @@ asmlinkage __visible void __init xen_start_kernel(void)
>  
>       xen_setup_runstate_info(0);
>  
> +     efi_systab_xen = xen_efi_probe();
> +
> +     if (efi_systab_xen) {
> +             strncpy((char *)&boot_params.efi_info.efi_loader_signature, 
> "Xen",
> +                             
> sizeof(boot_params.efi_info.efi_loader_signature));
> +             boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
> +             boot_params.efi_info.efi_systab_hi = 
> (__u32)(__pa(efi_systab_xen) >> 32);
> +
> +             set_bit(EFI_BOOT, &efi.flags);
> +             set_bit(EFI_NO_DIRECT, &efi.flags);
> +             set_bit(EFI_64BIT, &efi.flags);
> +     }
> +
>       /* Start the world */
>  #ifdef CONFIG_X86_32
>       i386_start_kernel();
> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index 38fb36e..8bc0183 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -240,4 +240,8 @@ config XEN_MCE_LOG
>  config XEN_HAVE_PVMMU
>         bool
>  
> +config XEN_EFI
> +     def_bool y
> +     depends on X86_64 && EFI
> +
>  endmenu
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index 45e00af..84044b5 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -9,6 +9,8 @@ obj-y += xenbus/
>  nostackp := $(call cc-option, -fno-stack-protector)
>  CFLAGS_features.o                    := $(nostackp)
>  
> +CFLAGS_efi.o                         += -fshort-wchar
> +
>  dom0-$(CONFIG_PCI) += pci.o
>  dom0-$(CONFIG_USB_SUPPORT) += dbgp.o
>  dom0-$(CONFIG_ACPI) += acpi.o $(xen-pad-y)
> @@ -33,6 +35,7 @@ obj-$(CONFIG_XEN_STUB)                      += xen-stub.o
>  obj-$(CONFIG_XEN_ACPI_HOTPLUG_MEMORY)        += xen-acpi-memhotplug.o
>  obj-$(CONFIG_XEN_ACPI_HOTPLUG_CPU)   += xen-acpi-cpuhotplug.o
>  obj-$(CONFIG_XEN_ACPI_PROCESSOR)     += xen-acpi-processor.o
> +obj-$(CONFIG_XEN_EFI)                        += efi.o
>  xen-evtchn-y                         := evtchn.o
>  xen-gntdev-y                         := gntdev.o
>  xen-gntalloc-y                               := gntalloc.o
> diff --git a/drivers/xen/efi.c b/drivers/xen/efi.c
> new file mode 100644
> index 0000000..e3d6618
> --- /dev/null
> +++ b/drivers/xen/efi.c
> @@ -0,0 +1,374 @@
> +/*
> + * EFI support for Xen.
> + *
> + * Copyright (C) 1999 VA Linux Systems
> + * Copyright (C) 1999 Walt Drummond <drummond@xxxxxxxxxxx>
> + * Copyright (C) 1999-2002 Hewlett-Packard Co.
> + *   David Mosberger-Tang <davidm@xxxxxxxxxx>
> + *   Stephane Eranian <eranian@xxxxxxxxxx>
> + * Copyright (C) 2005-2008 Intel Co.
> + *   Fenghua Yu <fenghua.yu@xxxxxxxxx>
> + *   Bibo Mao <bibo.mao@xxxxxxxxx>
> + *   Chandramouli Narayanan <mouli@xxxxxxxxxxxxxxx>
> + *   Huang Ying <ying.huang@xxxxxxxxx>
> + * Copyright (C) 2011 Novell Co.
> + *   Jan Beulich <JBeulich@xxxxxxxx>
> + * Copyright (C) 2011-2012 Oracle Co.
> + *   Liang Tang <liang.tang@xxxxxxxxxx>
> + * Copyright (c) 2014 Oracle Corporation, Daniel Kiper
> + */
> +
> +#include <linux/bug.h>
> +#include <linux/efi.h>
> +#include <linux/init.h>
> +#include <linux/string.h>
> +
> +#include <xen/interface/xen.h>
> +#include <xen/interface/platform.h>
> +
> +#include <asm/xen/hypercall.h>
> +
> +#define INIT_EFI_OP(name) \
> +     {.cmd = XENPF_efi_runtime_call, \
> +      .u.efi_runtime_call.function = XEN_EFI_##name, \
> +      .u.efi_runtime_call.misc = 0}
> +
> +#define efi_data(op) (op.u.efi_runtime_call)
> +
> +static efi_status_t xen_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(get_time);
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     if (tm) {
> +             BUILD_BUG_ON(sizeof(*tm) != 
> sizeof(efi_data(op).u.get_time.time));
> +             memcpy(tm, &efi_data(op).u.get_time.time, sizeof(*tm));
> +     }
> +
> +     if (tc) {
> +             tc->resolution = efi_data(op).u.get_time.resolution;
> +             tc->accuracy = efi_data(op).u.get_time.accuracy;
> +             tc->sets_to_zero = !!(efi_data(op).misc &
> +                                   XEN_EFI_GET_TIME_SET_CLEARS_NS);
> +     }
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_set_time(efi_time_t *tm)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(set_time);
> +
> +     BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.set_time));
> +     memcpy(&efi_data(op).u.set_time, tm, sizeof(*tm));
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_get_wakeup_time(efi_bool_t *enabled,
> +                                         efi_bool_t *pending,
> +                                         efi_time_t *tm)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(get_wakeup_time);
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     if (tm) {
> +             BUILD_BUG_ON(sizeof(*tm) != 
> sizeof(efi_data(op).u.get_wakeup_time));
> +             memcpy(tm, &efi_data(op).u.get_wakeup_time, sizeof(*tm));
> +     }
> +
> +     if (enabled)
> +             *enabled = !!(efi_data(op).misc & 
> XEN_EFI_GET_WAKEUP_TIME_ENABLED);
> +
> +     if (pending)
> +             *pending = !!(efi_data(op).misc & 
> XEN_EFI_GET_WAKEUP_TIME_PENDING);
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t 
> *tm)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(set_wakeup_time);
> +
> +     BUILD_BUG_ON(sizeof(*tm) != sizeof(efi_data(op).u.set_wakeup_time));
> +     if (enabled)
> +             efi_data(op).misc = XEN_EFI_SET_WAKEUP_TIME_ENABLE;
> +     if (tm)
> +             memcpy(&efi_data(op).u.set_wakeup_time, tm, sizeof(*tm));
> +     else
> +             efi_data(op).misc |= XEN_EFI_SET_WAKEUP_TIME_ENABLE_ONLY;
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_get_variable(efi_char16_t *name,
> +                                      efi_guid_t *vendor,
> +                                      u32 *attr,
> +                                      unsigned long *data_size,
> +                                      void *data)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(get_variable);
> +
> +     set_xen_guest_handle(efi_data(op).u.get_variable.name, name);
> +     BUILD_BUG_ON(sizeof(*vendor) !=
> +                  sizeof(efi_data(op).u.get_variable.vendor_guid));
> +     memcpy(&efi_data(op).u.get_variable.vendor_guid, vendor, 
> sizeof(*vendor));
> +     efi_data(op).u.get_variable.size = *data_size;
> +     set_xen_guest_handle(efi_data(op).u.get_variable.data, data);
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     *data_size = efi_data(op).u.get_variable.size;
> +     if (attr)
> +             *attr = efi_data(op).misc;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_get_next_variable(unsigned long *name_size,
> +                                           efi_char16_t *name,
> +                                           efi_guid_t *vendor)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(get_next_variable_name);
> +
> +     efi_data(op).u.get_next_variable_name.size = *name_size;
> +     set_xen_guest_handle(efi_data(op).u.get_next_variable_name.name, name);
> +     BUILD_BUG_ON(sizeof(*vendor) !=
> +                  sizeof(efi_data(op).u.get_next_variable_name.vendor_guid));
> +     memcpy(&efi_data(op).u.get_next_variable_name.vendor_guid, vendor,
> +            sizeof(*vendor));
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     *name_size = efi_data(op).u.get_next_variable_name.size;
> +     memcpy(vendor, &efi_data(op).u.get_next_variable_name.vendor_guid,
> +            sizeof(*vendor));
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_set_variable(efi_char16_t *name,
> +                                      efi_guid_t *vendor,
> +                                      u32 attr,
> +                                      unsigned long data_size,
> +                                      void *data)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(set_variable);
> +
> +     set_xen_guest_handle(efi_data(op).u.set_variable.name, name);
> +     efi_data(op).misc = attr;
> +     BUILD_BUG_ON(sizeof(*vendor) !=
> +                  sizeof(efi_data(op).u.set_variable.vendor_guid));
> +     memcpy(&efi_data(op).u.set_variable.vendor_guid, vendor, 
> sizeof(*vendor));
> +     efi_data(op).u.set_variable.size = data_size;
> +     set_xen_guest_handle(efi_data(op).u.set_variable.data, data);
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_query_variable_info(u32 attr,
> +                                             u64 *storage_space,
> +                                             u64 *remaining_space,
> +                                             u64 *max_variable_size)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(query_variable_info);
> +
> +     if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
> +             return EFI_UNSUPPORTED;
> +
> +     efi_data(op).u.query_variable_info.attr = attr;
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     *storage_space = efi_data(op).u.query_variable_info.max_store_size;
> +     *remaining_space = efi_data(op).u.query_variable_info.remain_store_size;
> +     *max_variable_size = efi_data(op).u.query_variable_info.max_size;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_get_next_high_mono_count(u32 *count)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(get_next_high_monotonic_count);
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     *count = efi_data(op).misc;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_update_capsule(efi_capsule_header_t **capsules,
> +                                        unsigned long count,
> +                                        unsigned long sg_list)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(update_capsule);
> +
> +     if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
> +             return EFI_UNSUPPORTED;
> +
> +     set_xen_guest_handle(efi_data(op).u.update_capsule.capsule_header_array,
> +                          capsules);
> +     efi_data(op).u.update_capsule.capsule_count = count;
> +     efi_data(op).u.update_capsule.sg_list = sg_list;
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_status_t xen_efi_query_capsule_caps(efi_capsule_header_t 
> **capsules,
> +                                            unsigned long count,
> +                                            u64 *max_size,
> +                                            int *reset_type)
> +{
> +     struct xen_platform_op op = INIT_EFI_OP(query_capsule_capabilities);
> +
> +     if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
> +             return EFI_UNSUPPORTED;
> +
> +     
> set_xen_guest_handle(efi_data(op).u.query_capsule_capabilities.capsule_header_array,
> +                                     capsules);
> +     efi_data(op).u.query_capsule_capabilities.capsule_count = count;
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             return EFI_UNSUPPORTED;
> +
> +     *max_size = efi_data(op).u.query_capsule_capabilities.max_capsule_size;
> +     *reset_type = efi_data(op).u.query_capsule_capabilities.reset_type;
> +
> +     return efi_data(op).status;
> +}
> +
> +static efi_char16_t vendor[100] __initdata;
> +
> +static efi_system_table_t efi_systab_xen __initdata = {
> +     .hdr = {
> +             .signature      = EFI_SYSTEM_TABLE_SIGNATURE,
> +             .revision       = 0, /* Initialized later. */
> +             .headersize     = 0, /* Ignored by Linux Kernel. */
> +             .crc32          = 0, /* Ignored by Linux Kernel. */
> +             .reserved       = 0
> +     },
> +     .fw_vendor      = EFI_INVALID_TABLE_ADDR, /* Initialized later. */
> +     .fw_revision    = 0,                      /* Initialized later. */
> +     .con_in_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .con_in         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .con_out_handle = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .con_out        = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .stderr_handle  = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .stderr         = EFI_INVALID_TABLE_ADDR, /* Not used under Xen. */
> +     .runtime        = (efi_runtime_services_t *)EFI_INVALID_TABLE_ADDR,
> +                                               /* Not used under Xen. */
> +     .boottime       = (efi_boot_services_t *)EFI_INVALID_TABLE_ADDR,
> +                                               /* Not used under Xen. */
> +     .nr_tables      = 0,                      /* Initialized later. */
> +     .tables         = EFI_INVALID_TABLE_ADDR  /* Initialized later. */
> +};
> +
> +static const struct efi efi_xen __initconst = {
> +     .systab                   = NULL, /* Initialized later. */
> +     .runtime_version          = 0,    /* Initialized later. */
> +     .mps                      = EFI_INVALID_TABLE_ADDR,
> +     .acpi                     = EFI_INVALID_TABLE_ADDR,
> +     .acpi20                   = EFI_INVALID_TABLE_ADDR,
> +     .smbios                   = EFI_INVALID_TABLE_ADDR,
> +     .sal_systab               = EFI_INVALID_TABLE_ADDR,
> +     .boot_info                = EFI_INVALID_TABLE_ADDR,
> +     .hcdp                     = EFI_INVALID_TABLE_ADDR,
> +     .uga                      = EFI_INVALID_TABLE_ADDR,
> +     .uv_systab                = EFI_INVALID_TABLE_ADDR,
> +     .fw_vendor                = EFI_INVALID_TABLE_ADDR,
> +     .runtime                  = EFI_INVALID_TABLE_ADDR,
> +     .config_table             = EFI_INVALID_TABLE_ADDR,
> +     .get_time                 = xen_efi_get_time,
> +     .set_time                 = xen_efi_set_time,
> +     .get_wakeup_time          = xen_efi_get_wakeup_time,
> +     .set_wakeup_time          = xen_efi_set_wakeup_time,
> +     .get_variable             = xen_efi_get_variable,
> +     .get_next_variable        = xen_efi_get_next_variable,
> +     .set_variable             = xen_efi_set_variable,
> +     .query_variable_info      = xen_efi_query_variable_info,
> +     .update_capsule           = xen_efi_update_capsule,
> +     .query_capsule_caps       = xen_efi_query_capsule_caps,
> +     .get_next_high_mono_count = xen_efi_get_next_high_mono_count,
> +     .reset_system             = NULL, /* Functionality provided by Xen. */
> +     .set_virtual_address_map  = NULL, /* Not used under Xen. */
> +     .memmap                   = NULL, /* Not used under Xen. */
> +     .flags                    = 0     /* Initialized later. */
> +};
> +
> +efi_system_table_t __init *xen_efi_probe(void)
> +{
> +     struct xen_platform_op op = {
> +             .cmd = XENPF_firmware_info,
> +             .u.firmware_info = {
> +                     .type = XEN_FW_EFI_INFO,
> +                     .index = XEN_FW_EFI_CONFIG_TABLE
> +             }
> +     };
> +     union xenpf_efi_info *info = &op.u.firmware_info.u.efi_info;
> +
> +     if (!xen_initial_domain() || HYPERVISOR_dom0_op(&op) < 0)
> +             return NULL;
> +
> +     /* Here we know that Xen runs on EFI platform. */
> +
> +     efi = efi_xen;
> +
> +     op.cmd = XENPF_firmware_info;
> +     op.u.firmware_info.type = XEN_FW_EFI_INFO;
> +     op.u.firmware_info.index = XEN_FW_EFI_VENDOR;
> +     info->vendor.bufsz = sizeof(vendor);
> +     set_xen_guest_handle(info->vendor.name, vendor);
> +
> +     if (HYPERVISOR_dom0_op(&op) == 0) {
> +             efi_systab_xen.fw_vendor = __pa_symbol(vendor);
> +             efi_systab_xen.fw_revision = info->vendor.revision;
> +     } else
> +             efi_systab_xen.fw_vendor = __pa_symbol(L"UNKNOWN");
> +
> +     op.cmd = XENPF_firmware_info;
> +     op.u.firmware_info.type = XEN_FW_EFI_INFO;
> +     op.u.firmware_info.index = XEN_FW_EFI_VERSION;
> +
> +     if (HYPERVISOR_dom0_op(&op) == 0)
> +             efi_systab_xen.hdr.revision = info->version;
> +
> +     op.cmd = XENPF_firmware_info;
> +     op.u.firmware_info.type = XEN_FW_EFI_INFO;
> +     op.u.firmware_info.index = XEN_FW_EFI_RT_VERSION;
> +
> +     if (HYPERVISOR_dom0_op(&op) == 0)
> +             efi.runtime_version = info->version;
> +
> +     op.cmd = XENPF_firmware_info;
> +     op.u.firmware_info.type = XEN_FW_EFI_INFO;
> +     op.u.firmware_info.index = XEN_FW_EFI_CONFIG_TABLE;
> +
> +     if (HYPERVISOR_dom0_op(&op) < 0)
> +             BUG();

Is it really worth of a BUG()? Can't we just print a warning and return
NULL? We could still boot without EFI support.

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