[PATCH v3 0/2] kernel: add new infrastructure for platform_has() support

[PATCH v3 0/2] kernel: add new infrastructure for platform_has() support

[Juergen Gross]

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@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

[PATCH v3 0/2] kernel: add new infrastructure for platform_has() support

[Juergen Gross via Virtualization]

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@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

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

[PATCH v3 1/2] kernel: add platform_has() infrastructure

[Juergen Gross]

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@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@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@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

[PATCH v3 1/2] kernel: add platform_has() infrastructure

[Juergen Gross via Virtualization]

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@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@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@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

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

[PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Juergen Gross]

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@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

[PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Juergen Gross via Virtualization]

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@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

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Re: [PATCH v3 0/2] kernel: add new infrastructure for platform_has() support

[Oleksandr]

On 04.05.22 18:57, Juergen Gross wrote:


Hello Juergen

> 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@gmail.com/T/#t


For both patches:

Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


Also I haven't faced any issues with testing current series (w/ and w/o 
xen-virtio series [1] applied) in Xen guest (Linux v5.18-rc4) on Arm64 
based board.

So, you can also add:

[Arm64 only]

Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


Thanks!


Note, I reworked patch #3 [1] to use new platform_xxx functionality:


diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 07eb69f..1f9c3ba 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -443,6 +443,8 @@ static int __init xen_guest_init(void)
         if (!xen_domain())
                 return 0;

+       xen_set_restricted_virtio_memory_access();
+
         if (!acpi_disabled)
                 xen_acpi_guest_init();
         else
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index 517a9d8..8b71b1d 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -195,6 +195,8 @@ static void __init xen_hvm_guest_init(void)
         if (xen_pv_domain())
                 return;

+       xen_set_restricted_virtio_memory_access();
+
         init_hvm_pv_info();

         reserve_shared_info();
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 5038edb..fcd5d5d 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -109,6 +109,8 @@ static DEFINE_PER_CPU(struct tls_descs, 
shadow_tls_desc);

  static void __init xen_pv_init_platform(void)
  {
+       xen_set_restricted_virtio_memory_access();
+
         populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));

         set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info);
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 313a9127..a7bd8ce 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -339,4 +339,15 @@ config XEN_GRANT_DMA_OPS
         bool
         select DMA_OPS

+config XEN_VIRTIO
+       bool "Xen virtio support"
+       depends on VIRTIO
+       select XEN_GRANT_DMA_OPS
+       help
+         Enable virtio support for running as Xen guest. Depending on the
+         guest type this will require special support on the backend side
+         (qemu or kernel, depending on the virtio device types used).
+
+         If in doubt, say n.
+
  endmenu
diff --git a/include/xen/xen.h b/include/xen/xen.h
index a99bab8..0780a81 100644
--- a/include/xen/xen.h
+++ b/include/xen/xen.h
@@ -52,6 +52,14 @@ bool xen_biovec_phys_mergeable(const struct bio_vec 
*vec1,
  extern u64 xen_saved_max_mem_size;
  #endif

+#include <linux/platform-feature.h>
+
+static inline void xen_set_restricted_virtio_memory_access(void)
+{
+       if (IS_ENABLED(CONFIG_XEN_VIRTIO) && xen_domain())
+ platform_set(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS);
+}
+
  #ifdef CONFIG_XEN_UNPOPULATED_ALLOC
  int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page 
**pages);
  void xen_free_unpopulated_pages(unsigned int nr_pages, struct page 
**pages);
(END)






>
> 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
>
-- 
Regards,

Oleksandr Tyshchenko

Re: [PATCH v3 1/2] kernel: add platform_has() infrastructure

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
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Re: [PATCH v3 1/2] kernel: add platform_has() infrastructure

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
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Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v3 1/2] kernel: add platform_has() infrastructure

[Boris Petkov]

On May 4, 2022 5:57:02 PM GMT+02:00, Juergen Gross <jgross@suse.com> wrote:
>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@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

Nice and simple, I like.

Acked-by: Borislav Petkov <bp@suse.de>
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Re: [PATCH v3 1/2] kernel: add platform_has() infrastructure

[Boris Petkov]

On May 4, 2022 5:57:02 PM GMT+02:00, Juergen Gross <jgross@suse.com> wrote:
>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@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

Nice and simple, I like.

Acked-by: Borislav Petkov <bp@suse.de>
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Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Boris Petkov]

On May 4, 2022 3:57:03 PM UTC, Juergen Gross <jgross@suse.com> wrote:
>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@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(-)

Acked-by: Borislav Petkov <bp@suse.de>
-- 
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Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Boris Petkov]

On May 4, 2022 3:57:03 PM UTC, Juergen Gross <jgross@suse.com> wrote:
>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@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(-)

Acked-by: Borislav Petkov <bp@suse.de>
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Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Juergen Gross via Virtualization]

[-- Attachment #1.1.1.1: Type: text/plain, Size: 7665 bytes --]

On 04.05.22 17:57, Juergen Gross wrote:
> 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@suse.com>

Could I get some feedback from the s390 side, please?


Juergen

> ---
> 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 */


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_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [PATCH v3 2/2] virtio: replace arch_has_restricted_virtio_memory_access()

[Juergen Gross]

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On 04.05.22 17:57, Juergen Gross wrote:
> 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@suse.com>

Could I get some feedback from the s390 side, please?


Juergen

> ---
> 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 */


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