Juergen Gross
2022-May-04 15:57 UTC
[PATCH v3 0/2] kernel: add new infrastructure for platform_has() support
In another patch series [1] the need has come up to have support for a generic feature flag infrastructure. This patch series is introducing that infrastructure and adds the first use case. I have decided to use a similar interface as the already known x86 cpu_has() function. As the new infrastructure is meant to be usable for general and arch-specific feature flags, the flags are being spread between a general bitmap and an arch specific one. The bitmaps start all being zero, single features can be set or reset at any time by using the related platform_[re]set_feature() functions. The platform_has() function is using a simple test_bit() call for now, further optimization might be added when needed. [1]: https://lore.kernel.org/lkml/1650646263-22047-1-git-send-email-olekstysh at gmail.com/T/#t Juergen Gross (2): kernel: add platform_has() infrastructure virtio: replace arch_has_restricted_virtio_memory_access() MAINTAINERS | 8 ++++++++ arch/s390/Kconfig | 1 - arch/s390/mm/init.c | 13 +++---------- arch/x86/Kconfig | 1 - arch/x86/mm/mem_encrypt.c | 7 ------- arch/x86/mm/mem_encrypt_amd.c | 4 ++++ drivers/virtio/Kconfig | 6 ------ drivers/virtio/virtio.c | 5 ++--- include/asm-generic/Kbuild | 1 + include/asm-generic/platform-feature.h | 8 ++++++++ include/linux/platform-feature.h | 19 ++++++++++++++++++ include/linux/virtio_config.h | 9 --------- kernel/Makefile | 2 +- kernel/platform-feature.c | 27 ++++++++++++++++++++++++++ 14 files changed, 73 insertions(+), 38 deletions(-) create mode 100644 include/asm-generic/platform-feature.h create mode 100644 include/linux/platform-feature.h create mode 100644 kernel/platform-feature.c -- 2.35.3
Juergen Gross
2022-May-04 15:57 UTC
[PATCH v3 1/2] kernel: add platform_has() infrastructure
Add a simple infrastructure for setting, resetting and querying
platform feature flags.
Flags can be either global or architecture specific.
Signed-off-by: Juergen Gross <jgross at suse.com>
---
V2:
- rename set/reset functions to platform_[set|clear]() (Boris Petkov,
Heiko Carstens)
- move function implementations to c file (Boris Petkov)
---
MAINTAINERS | 8 ++++++++
include/asm-generic/Kbuild | 1 +
include/asm-generic/platform-feature.h | 8 ++++++++
include/linux/platform-feature.h | 15 ++++++++++++++
kernel/Makefile | 2 +-
kernel/platform-feature.c | 27 ++++++++++++++++++++++++++
6 files changed, 60 insertions(+), 1 deletion(-)
create mode 100644 include/asm-generic/platform-feature.h
create mode 100644 include/linux/platform-feature.h
create mode 100644 kernel/platform-feature.c
diff --git a/MAINTAINERS b/MAINTAINERS
index edc96cdb85e8..2749a88d75f2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15657,6 +15657,14 @@ S: Maintained
F: Documentation/devicetree/bindings/iio/chemical/plantower,pms7003.yaml
F: drivers/iio/chemical/pms7003.c
+PLATFORM FEATURE INFRASTRUCTURE
+M: Juergen Gross <jgross at suse.com>
+S: Maintained
+F: arch/*/include/asm/platform-feature.h
+F: include/asm-generic/platform-feature.h
+F: include/linux/platform-feature.h
+F: kernel/platform-feature.c
+
PLDMFW LIBRARY
M: Jacob Keller <jacob.e.keller at intel.com>
S: Maintained
diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index 302506bbc2a4..8e47d483b524 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -44,6 +44,7 @@ mandatory-y += msi.h
mandatory-y += pci.h
mandatory-y += percpu.h
mandatory-y += pgalloc.h
+mandatory-y += platform-feature.h
mandatory-y += preempt.h
mandatory-y += rwonce.h
mandatory-y += sections.h
diff --git a/include/asm-generic/platform-feature.h
b/include/asm-generic/platform-feature.h
new file mode 100644
index 000000000000..4b0af3d51588
--- /dev/null
+++ b/include/asm-generic/platform-feature.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_PLATFORM_FEATURE_H
+#define _ASM_GENERIC_PLATFORM_FEATURE_H
+
+/* Number of arch specific feature flags. */
+#define PLATFORM_ARCH_FEAT_N 0
+
+#endif /* _ASM_GENERIC_PLATFORM_FEATURE_H */
diff --git a/include/linux/platform-feature.h b/include/linux/platform-feature.h
new file mode 100644
index 000000000000..6ed859928b97
--- /dev/null
+++ b/include/linux/platform-feature.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PLATFORM_FEATURE_H
+#define _PLATFORM_FEATURE_H
+
+#include <linux/bitops.h>
+#include <asm/platform-feature.h>
+
+/* The platform features are starting with the architecture specific ones. */
+#define PLATFORM_FEAT_N (0 + PLATFORM_ARCH_FEAT_N)
+
+void platform_set(unsigned int feature);
+void platform_clear(unsigned int feature);
+bool platform_has(unsigned int feature);
+
+#endif /* _PLATFORM_FEATURE_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index 847a82bfe0e3..2f412f80110d 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -7,7 +7,7 @@ obj-y = fork.o exec_domain.o panic.o \
cpu.o exit.o softirq.o resource.o \
sysctl.o capability.o ptrace.o user.o \
signal.o sys.o umh.o workqueue.o pid.o task_work.o \
- extable.o params.o \
+ extable.o params.o platform-feature.o \
kthread.o sys_ni.o nsproxy.o \
notifier.o ksysfs.o cred.o reboot.o \
async.o range.o smpboot.o ucount.o regset.o
diff --git a/kernel/platform-feature.c b/kernel/platform-feature.c
new file mode 100644
index 000000000000..cb6a6c3e4fed
--- /dev/null
+++ b/kernel/platform-feature.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitops.h>
+#include <linux/cache.h>
+#include <linux/export.h>
+#include <linux/platform-feature.h>
+
+#define PLATFORM_FEAT_ARRAY_SZ BITS_TO_LONGS(PLATFORM_FEAT_N)
+static unsigned long __read_mostly platform_features[PLATFORM_FEAT_ARRAY_SZ];
+
+void platform_set(unsigned int feature)
+{
+ set_bit(feature, platform_features);
+}
+EXPORT_SYMBOL_GPL(platform_set);
+
+void platform_clear(unsigned int feature)
+{
+ clear_bit(feature, platform_features);
+}
+EXPORT_SYMBOL_GPL(platform_clear);
+
+bool platform_has(unsigned int feature)
+{
+ return test_bit(feature, platform_features);
+}
+EXPORT_SYMBOL_GPL(platform_has);
--
2.35.3
Juergen Gross
2022-May-04 15:57 UTC
[PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()
Instead of using arch_has_restricted_virtio_memory_access() together
with CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, replace those
with platform_has() and a new platform feature
PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS.
Signed-off-by: Juergen Gross <jgross at suse.com>
---
V2:
- move setting of PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS in SEV case
to sev_setup_arch().
V3:
- remove Hyper-V chunk (Michael Kelley)
- remove include virtio_config.h from mem_encrypt.c (Oleksandr Tyshchenko)
- add comment for PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS (Oleksandr Tyshchenko)
---
arch/s390/Kconfig | 1 -
arch/s390/mm/init.c | 13 +++----------
arch/x86/Kconfig | 1 -
arch/x86/mm/mem_encrypt.c | 7 -------
arch/x86/mm/mem_encrypt_amd.c | 4 ++++
drivers/virtio/Kconfig | 6 ------
drivers/virtio/virtio.c | 5 ++---
include/linux/platform-feature.h | 6 +++++-
include/linux/virtio_config.h | 9 ---------
9 files changed, 14 insertions(+), 38 deletions(-)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index e084c72104f8..f97a22ae69a8 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -772,7 +772,6 @@ menu "Virtualization"
config PROTECTED_VIRTUALIZATION_GUEST
def_bool n
prompt "Protected virtualization guest support"
- select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
help
Select this option, if you want to be able to run this
kernel as a protected virtualization KVM guest.
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 86ffd0d51fd5..2c3b451813ed 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -31,6 +31,7 @@
#include <linux/cma.h>
#include <linux/gfp.h>
#include <linux/dma-direct.h>
+#include <linux/platform-feature.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
@@ -168,22 +169,14 @@ bool force_dma_unencrypted(struct device *dev)
return is_prot_virt_guest();
}
-#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
-
-int arch_has_restricted_virtio_memory_access(void)
-{
- return is_prot_virt_guest();
-}
-EXPORT_SYMBOL(arch_has_restricted_virtio_memory_access);
-
-#endif
-
/* protected virtualization */
static void pv_init(void)
{
if (!is_prot_virt_guest())
return;
+ platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
+
/* make sure bounce buffers are shared */
swiotlb_force = SWIOTLB_FORCE;
swiotlb_init(1);
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4bed3abf444d..eeb7c6c8eec5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1515,7 +1515,6 @@ config X86_CPA_STATISTICS
config X86_MEM_ENCRYPT
select ARCH_HAS_FORCE_DMA_UNENCRYPTED
select DYNAMIC_PHYSICAL_MASK
- select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
def_bool n
config AMD_MEM_ENCRYPT
diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
index 50d209939c66..18a55a0f1ca2 100644
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -12,7 +12,6 @@
#include <linux/swiotlb.h>
#include <linux/cc_platform.h>
#include <linux/mem_encrypt.h>
-#include <linux/virtio_config.h>
/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
@@ -76,9 +75,3 @@ void __init mem_encrypt_init(void)
print_mem_encrypt_feature_info();
}
-
-int arch_has_restricted_virtio_memory_access(void)
-{
- return cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT);
-}
-EXPORT_SYMBOL_GPL(arch_has_restricted_virtio_memory_access);
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 6169053c2854..39b71084d36b 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -21,6 +21,7 @@
#include <linux/dma-mapping.h>
#include <linux/virtio_config.h>
#include <linux/cc_platform.h>
+#include <linux/platform-feature.h>
#include <asm/tlbflush.h>
#include <asm/fixmap.h>
@@ -206,6 +207,9 @@ void __init sev_setup_arch(void)
size = total_mem * 6 / 100;
size = clamp_val(size, IO_TLB_DEFAULT_SIZE, SZ_1G);
swiotlb_adjust_size(size);
+
+ /* Set restricted memory access for virtio. */
+ platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
}
static unsigned long pg_level_to_pfn(int level, pte_t *kpte, pgprot_t
*ret_prot)
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index b5adf6abd241..a6dc8b5846fe 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -6,12 +6,6 @@ config VIRTIO
bus, such as CONFIG_VIRTIO_PCI, CONFIG_VIRTIO_MMIO, CONFIG_RPMSG
or CONFIG_S390_GUEST.
-config ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
- bool
- help
- This option is selected if the architecture may need to enforce
- VIRTIO_F_ACCESS_PLATFORM
-
config VIRTIO_PCI_LIB
tristate
help
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 22f15f444f75..371e16b18381 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -5,6 +5,7 @@
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/of.h>
+#include <linux/platform-feature.h>
#include <uapi/linux/virtio_ids.h>
/* Unique numbering for virtio devices. */
@@ -170,12 +171,10 @@ EXPORT_SYMBOL_GPL(virtio_add_status);
static int virtio_features_ok(struct virtio_device *dev)
{
unsigned status;
- int ret;
might_sleep();
- ret = arch_has_restricted_virtio_memory_access();
- if (ret) {
+ if (platform_has(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS)) {
if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
dev_warn(&dev->dev,
"device must provide VIRTIO_F_VERSION_1\n");
diff --git a/include/linux/platform-feature.h b/include/linux/platform-feature.h
index 6ed859928b97..b2f48be999fa 100644
--- a/include/linux/platform-feature.h
+++ b/include/linux/platform-feature.h
@@ -6,7 +6,11 @@
#include <asm/platform-feature.h>
/* The platform features are starting with the architecture specific ones. */
-#define PLATFORM_FEAT_N (0 + PLATFORM_ARCH_FEAT_N)
+
+/* Used to enable platform specific DMA handling for virtio devices. */
+#define PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS (0 + PLATFORM_ARCH_FEAT_N)
+
+#define PLATFORM_FEAT_N (1 + PLATFORM_ARCH_FEAT_N)
void platform_set(unsigned int feature);
void platform_clear(unsigned int feature);
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index b341dd62aa4d..79498298519d 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -559,13 +559,4 @@ static inline void virtio_cwrite64(struct virtio_device
*vdev,
_r; \
})
-#ifdef CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
-int arch_has_restricted_virtio_memory_access(void);
-#else
-static inline int arch_has_restricted_virtio_memory_access(void)
-{
- return 0;
-}
-#endif /* CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS */
-
#endif /* _LINUX_VIRTIO_CONFIG_H */
--
2.35.3