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

[Juergen Gross <jgross@xxxxxxxx>]

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@xxxxxxxx>
---
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