Juergen Gross
2022-Apr-26 13:40 UTC
[PATCH 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/kernel/cpu/mshyperv.c | 5 ++++- arch/x86/mm/mem_encrypt.c | 6 ------ arch/x86/mm/mem_encrypt_identity.c | 5 +++++ 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 | 30 ++++++++++++++++++++++++++ include/linux/virtio_config.h | 9 -------- kernel/Makefile | 2 +- kernel/platform-feature.c | 7 ++++++ 15 files changed, 69 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 -- 2.34.1
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> --- MAINTAINERS | 8 +++++++ include/asm-generic/Kbuild | 1 + include/asm-generic/platform-feature.h | 8 +++++++ include/linux/platform-feature.h | 29 ++++++++++++++++++++++++++ kernel/Makefile | 2 +- kernel/platform-feature.c | 7 +++++++ 6 files changed, 54 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 5e8c2f611766..eb943f089eda 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15650,6 +15650,14 @@ 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..df393d502a4f --- /dev/null +++ b/include/linux/platform-feature.h @@ -0,0 +1,29 @@ +/* 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) + +#define PLATFORM_FEAT_ARRAY_SZ BITS_TO_LONGS(PLATFORM_FEAT_N) +extern unsigned long platform_features[PLATFORM_FEAT_ARRAY_SZ]; + +static inline void platform_set_feature(unsigned int feature) +{ + set_bit(feature, platform_features); +} + +static inline void platform_reset_feature(unsigned int feature) +{ + clear_bit(feature, platform_features); +} + +static inline bool platform_has(unsigned int feature) +{ + return test_bit(feature, platform_features); +} + +#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..2d52f8442cd5 --- /dev/null +++ b/kernel/platform-feature.c @@ -0,0 +1,7 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/cache.h> +#include <linux/platform-feature.h> + +unsigned long __read_mostly platform_features[PLATFORM_FEAT_ARRAY_SZ]; +EXPORT_SYMBOL_GPL(platform_features); -- 2.34.1
Juergen Gross
2022-Apr-26 13:40 UTC
[PATCH 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> --- I've only done a compile test on x86 for now, as I can't test these changes easily (SEV might be doable for me, but s390 isn't). --- arch/s390/Kconfig | 1 - arch/s390/mm/init.c | 13 +++---------- arch/x86/Kconfig | 1 - arch/x86/kernel/cpu/mshyperv.c | 5 ++++- arch/x86/mm/mem_encrypt.c | 6 ------ arch/x86/mm/mem_encrypt_identity.c | 5 +++++ drivers/virtio/Kconfig | 6 ------ drivers/virtio/virtio.c | 5 ++--- include/linux/platform-feature.h | 3 ++- include/linux/virtio_config.h | 9 --------- 10 files changed, 16 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..8e4fa10c6b12 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_feature(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 b0142e01002e..20ac72546ae4 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/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 4b67094215bb..435611d83895 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -19,6 +19,7 @@ #include <linux/i8253.h> #include <linux/random.h> #include <linux/swiotlb.h> +#include <linux/platform-feature.h> #include <asm/processor.h> #include <asm/hypervisor.h> #include <asm/hyperv-tlfs.h> @@ -347,8 +348,10 @@ static void __init ms_hyperv_init_platform(void) #endif /* Isolation VMs are unenlightened SEV-based VMs, thus this check: */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { - if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE) + if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE) { cc_set_vendor(CC_VENDOR_HYPERV); + platform_set_feature(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS); + } } } diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 50d209939c66..9b6a7c98b2b1 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -76,9 +76,3 @@ 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_identity.c b/arch/x86/mm/mem_encrypt_identity.c index b43bc24d2bb6..6043ba6cd17d 100644 --- a/arch/x86/mm/mem_encrypt_identity.c +++ b/arch/x86/mm/mem_encrypt_identity.c @@ -40,6 +40,7 @@ #include <linux/mm.h> #include <linux/mem_encrypt.h> #include <linux/cc_platform.h> +#include <linux/platform-feature.h> #include <asm/setup.h> #include <asm/sections.h> @@ -566,6 +567,10 @@ void __init sme_enable(struct boot_params *bp) } else { /* SEV state cannot be controlled by a command line option */ sme_me_mask = me_mask; + + /* Set restricted memory access for virtio. */ + platform_set_feature(PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS); + goto out; } 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 df393d502a4f..34b649aaa1da 100644 --- a/include/linux/platform-feature.h +++ b/include/linux/platform-feature.h @@ -6,7 +6,8 @@ #include <asm/platform-feature.h> /* The platform features are starting with the architecture specific ones. */ -#define PLATFORM_FEAT_N (0 + PLATFORM_ARCH_FEAT_N) +#define PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS 0 +#define PLATFORM_FEAT_N (1 + PLATFORM_ARCH_FEAT_N) #define PLATFORM_FEAT_ARRAY_SZ BITS_TO_LONGS(PLATFORM_FEAT_N) extern unsigned long platform_features[PLATFORM_FEAT_ARRAY_SZ]; 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 */ -- 2.34.1