When efi-stub copies an EFI-provided confidential computing (coco)
secret area, reserve that memory block for future use within the kernel.
Signed-off-by: Dov Murik <[email protected]>
---
arch/x86/platform/efi/efi.c | 3 +++
drivers/firmware/efi/Makefile | 1 +
drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++
drivers/firmware/efi/efi.c | 8 +++++++
include/linux/efi.h | 10 +++++++++
5 files changed, 63 insertions(+)
create mode 100644 drivers/firmware/efi/coco.c
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 147c30a81f15..1591d67e0bcd 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -93,6 +93,9 @@ static const unsigned long * const efi_tables[] = {
#ifdef CONFIG_LOAD_UEFI_KEYS
&efi.mokvar_table,
#endif
+#ifdef CONFIG_EFI_COCO_SECRET
+ &efi.coco_secret,
+#endif
};
u64 efi_setup; /* efi setup_data physical address */
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index c02ff25dd477..49c4a8c0bfc4 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o
obj-$(CONFIG_EFI_RCI2_TABLE) += rci2-table.o
obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += embedded-firmware.o
obj-$(CONFIG_LOAD_UEFI_KEYS) += mokvar-table.o
+obj-$(CONFIG_EFI_COCO_SECRET) += coco.o
fake_map-y += fake_mem.o
fake_map-$(CONFIG_X86) += x86_fake_mem.o
diff --git a/drivers/firmware/efi/coco.c b/drivers/firmware/efi/coco.c
new file mode 100644
index 000000000000..42f477d6188c
--- /dev/null
+++ b/drivers/firmware/efi/coco.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Confidential computing (coco) secret area handling
+ *
+ * Copyright (C) 2021 IBM Corporation
+ * Author: Dov Murik <[email protected]>
+ */
+
+#define pr_fmt(fmt) "efi: " fmt
+
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <asm/early_ioremap.h>
+
+/*
+ * Reserve the confidential computing secret area memory
+ */
+int __init efi_coco_secret_area_reserve(void)
+{
+ struct linux_efi_coco_secret_area *secret_area;
+ unsigned long secret_area_size;
+
+ if (efi.coco_secret == EFI_INVALID_TABLE_ADDR)
+ return 0;
+
+ secret_area = early_memremap(efi.coco_secret, sizeof(*secret_area));
+ if (!secret_area) {
+ pr_err("Failed to map confidential computing secret area\n");
+ efi.coco_secret = EFI_INVALID_TABLE_ADDR;
+ return -ENOMEM;
+ }
+
+ secret_area_size = sizeof(*secret_area) + secret_area->size;
+ memblock_reserve(efi.coco_secret, secret_area_size);
+
+ pr_info("Reserved memory of EFI-provided confidential computing secret area");
+
+ early_memunmap(secret_area, sizeof(*secret_area));
+ return 0;
+}
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 847f33ffc4ae..31bdae2afc47 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -46,6 +46,9 @@ struct efi __read_mostly efi = {
#ifdef CONFIG_LOAD_UEFI_KEYS
.mokvar_table = EFI_INVALID_TABLE_ADDR,
#endif
+#ifdef CONFIG_EFI_COCO_SECRET
+ .coco_secret = EFI_INVALID_TABLE_ADDR,
+#endif
};
EXPORT_SYMBOL(efi);
@@ -525,6 +528,9 @@ static const efi_config_table_type_t common_tables[] __initconst = {
#endif
#ifdef CONFIG_LOAD_UEFI_KEYS
{LINUX_EFI_MOK_VARIABLE_TABLE_GUID, &efi.mokvar_table, "MOKvar" },
+#endif
+#ifdef CONFIG_EFI_COCO_SECRET
+ {LINUX_EFI_COCO_SECRET_AREA_GUID, &efi.coco_secret, "CocoSecret" },
#endif
{},
};
@@ -613,6 +619,8 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
efi_tpm_eventlog_init();
+ efi_coco_secret_area_reserve();
+
if (mem_reserve != EFI_INVALID_TABLE_ADDR) {
unsigned long prsv = mem_reserve;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 9021dd521302..6e57dd083e25 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -550,6 +550,7 @@ extern struct efi {
unsigned long tpm_log; /* TPM2 Event Log table */
unsigned long tpm_final_log; /* TPM2 Final Events Log table */
unsigned long mokvar_table; /* MOK variable config table */
+ unsigned long coco_secret; /* Confidential computing secret table */
efi_get_time_t *get_time;
efi_set_time_t *set_time;
@@ -1288,4 +1289,13 @@ struct linux_efi_coco_secret_area {
u8 area[];
};
+#ifdef CONFIG_EFI_COCO_SECRET
+extern int efi_coco_secret_area_reserve(void);
+#else
+static inline int efi_coco_secret_area_reserve(void)
+{
+ return 0;
+}
+#endif
+
#endif /* _LINUX_EFI_H */
--
2.25.1
On Wed, Oct 20, 2021 at 06:14:07AM +0000, Dov Murik wrote:
> When efi-stub copies an EFI-provided confidential computing (coco)
> secret area, reserve that memory block for future use within the kernel.
>
> Signed-off-by: Dov Murik <[email protected]>
> ---
> arch/x86/platform/efi/efi.c | 3 +++
> drivers/firmware/efi/Makefile | 1 +
> drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++
> drivers/firmware/efi/efi.c | 8 +++++++
> include/linux/efi.h | 10 +++++++++
> 5 files changed, 63 insertions(+)
> create mode 100644 drivers/firmware/efi/coco.c
>
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 147c30a81f15..1591d67e0bcd 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -93,6 +93,9 @@ static const unsigned long * const efi_tables[] = {
> #ifdef CONFIG_LOAD_UEFI_KEYS
> &efi.mokvar_table,
> #endif
> +#ifdef CONFIG_EFI_COCO_SECRET
> + &efi.coco_secret,
> +#endif
> };
>
> u64 efi_setup; /* efi setup_data physical address */
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index c02ff25dd477..49c4a8c0bfc4 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -32,6 +32,7 @@ obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o
> obj-$(CONFIG_EFI_RCI2_TABLE) += rci2-table.o
> obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += embedded-firmware.o
> obj-$(CONFIG_LOAD_UEFI_KEYS) += mokvar-table.o
> +obj-$(CONFIG_EFI_COCO_SECRET) += coco.o
>
> fake_map-y += fake_mem.o
> fake_map-$(CONFIG_X86) += x86_fake_mem.o
> diff --git a/drivers/firmware/efi/coco.c b/drivers/firmware/efi/coco.c
> new file mode 100644
> index 000000000000..42f477d6188c
> --- /dev/null
> +++ b/drivers/firmware/efi/coco.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Confidential computing (coco) secret area handling
> + *
> + * Copyright (C) 2021 IBM Corporation
> + * Author: Dov Murik <[email protected]>
> + */
> +
> +#define pr_fmt(fmt) "efi: " fmt
> +
> +#include <linux/efi.h>
> +#include <linux/init.h>
> +#include <linux/memblock.h>
> +#include <asm/early_ioremap.h>
> +
> +/*
> + * Reserve the confidential computing secret area memory
> + */
> +int __init efi_coco_secret_area_reserve(void)
> +{
> + struct linux_efi_coco_secret_area *secret_area;
> + unsigned long secret_area_size;
> +
> + if (efi.coco_secret == EFI_INVALID_TABLE_ADDR)
> + return 0;
> +
> + secret_area = early_memremap(efi.coco_secret, sizeof(*secret_area));
> + if (!secret_area) {
> + pr_err("Failed to map confidential computing secret area\n");
> + efi.coco_secret = EFI_INVALID_TABLE_ADDR;
> + return -ENOMEM;
> + }
> +
> + secret_area_size = sizeof(*secret_area) + secret_area->size;
> + memblock_reserve(efi.coco_secret, secret_area_size);
> +
> + pr_info("Reserved memory of EFI-provided confidential computing secret area");
When kernel code works properly, it is quiet. Why do you need to print
this out at every boot?
> +
> + early_memunmap(secret_area, sizeof(*secret_area));
> + return 0;
> +}
And again, when is this memory freed when shutting down?
thanks,
greg k-h
On 20/10/2021 9:40, Greg KH wrote:
> On Wed, Oct 20, 2021 at 06:14:07AM +0000, Dov Murik wrote:
>> When efi-stub copies an EFI-provided confidential computing (coco)
>> secret area, reserve that memory block for future use within the kernel.
>>
>> Signed-off-by: Dov Murik <[email protected]>
>> ---
>> arch/x86/platform/efi/efi.c | 3 +++
>> drivers/firmware/efi/Makefile | 1 +
>> drivers/firmware/efi/coco.c | 41 +++++++++++++++++++++++++++++++++++
>> drivers/firmware/efi/efi.c | 8 +++++++
>> include/linux/efi.h | 10 +++++++++
>> 5 files changed, 63 insertions(+)
>> create mode 100644 drivers/firmware/efi/coco.c
>>
>> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
>> index 147c30a81f15..1591d67e0bcd 100644
>> --- a/arch/x86/platform/efi/efi.c
>> +++ b/arch/x86/platform/efi/efi.c
>> @@ -93,6 +93,9 @@ static const unsigned long * const efi_tables[] = {
>> #ifdef CONFIG_LOAD_UEFI_KEYS
>> &efi.mokvar_table,
>> #endif
>> +#ifdef CONFIG_EFI_COCO_SECRET
>> + &efi.coco_secret,
>> +#endif
>> };
>>
>> u64 efi_setup; /* efi setup_data physical address */
>> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
>> index c02ff25dd477..49c4a8c0bfc4 100644
>> --- a/drivers/firmware/efi/Makefile
>> +++ b/drivers/firmware/efi/Makefile
>> @@ -32,6 +32,7 @@ obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o
>> obj-$(CONFIG_EFI_RCI2_TABLE) += rci2-table.o
>> obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE) += embedded-firmware.o
>> obj-$(CONFIG_LOAD_UEFI_KEYS) += mokvar-table.o
>> +obj-$(CONFIG_EFI_COCO_SECRET) += coco.o
>>
>> fake_map-y += fake_mem.o
>> fake_map-$(CONFIG_X86) += x86_fake_mem.o
>> diff --git a/drivers/firmware/efi/coco.c b/drivers/firmware/efi/coco.c
>> new file mode 100644
>> index 000000000000..42f477d6188c
>> --- /dev/null
>> +++ b/drivers/firmware/efi/coco.c
>> @@ -0,0 +1,41 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Confidential computing (coco) secret area handling
>> + *
>> + * Copyright (C) 2021 IBM Corporation
>> + * Author: Dov Murik <[email protected]>
>> + */
>> +
>> +#define pr_fmt(fmt) "efi: " fmt
>> +
>> +#include <linux/efi.h>
>> +#include <linux/init.h>
>> +#include <linux/memblock.h>
>> +#include <asm/early_ioremap.h>
>> +
>> +/*
>> + * Reserve the confidential computing secret area memory
>> + */
>> +int __init efi_coco_secret_area_reserve(void)
>> +{
>> + struct linux_efi_coco_secret_area *secret_area;
>> + unsigned long secret_area_size;
>> +
>> + if (efi.coco_secret == EFI_INVALID_TABLE_ADDR)
>> + return 0;
>> +
>> + secret_area = early_memremap(efi.coco_secret, sizeof(*secret_area));
>> + if (!secret_area) {
>> + pr_err("Failed to map confidential computing secret area\n");
>> + efi.coco_secret = EFI_INVALID_TABLE_ADDR;
>> + return -ENOMEM;
>> + }
>> +
>> + secret_area_size = sizeof(*secret_area) + secret_area->size;
>> + memblock_reserve(efi.coco_secret, secret_area_size);
>> +
>> + pr_info("Reserved memory of EFI-provided confidential computing secret area");
>
> When kernel code works properly, it is quiet. Why do you need to print
> this out at every boot?
>
My kernel is not so quiet at the info loglevel; specifically from efi I
see these prints (third log line added by this patch):
[ 0.000000] efi: EFI v2.70 by EDK II
[ 0.000000] efi: SMBIOS=0x7f541000 ACPI=0x7f77e000 ACPI 2.0=0x7f77e014 MEMATTR=0x7ea0c018 CocoSecret=0x7ea0b018
[ 0.000000] efi: Reserved memory of EFI-provided confidential computing secret area
This print is useful to understand that both OVMF (EFI) and kernel support
the confidential computing secret area.
>> +
>> + early_memunmap(secret_area, sizeof(*secret_area));
>> + return 0;
>> +}
>
> And again, when is this memory freed when shutting down?
>
It is currently not freed. I tried to look for such memory freeing of
other EFI-provided memory areas (such as efi.tpm_final_log) and couldn't
find them. Can you please share pointers/examples of how to do that?
Thanks,
-Dov