From: <ankita@nvidia.com> To: <ankita@nvidia.com>, <jgg@nvidia.com>, <maz@kernel.org>, <oliver.upton@linux.dev>, <james.morse@arm.com>, <suzuki.poulose@arm.com>, <yuzenghui@huawei.com>, <reinette.chatre@intel.com>, <surenb@google.com>, <stefanha@redhat.com>, <brauner@kernel.org>, <catalin.marinas@arm.com>, <will@kernel.org>, <mark.rutland@arm.com>, <alex.williamson@redhat.com>, <kevin.tian@intel.com>, <yi.l.liu@intel.com>, <ardb@kernel.org>, <akpm@linux-foundation.org>, <andreyknvl@gmail.com>, <wangjinchao@xfusion.com>, <gshan@redhat.com>, <shahuang@redhat.com>, <ricarkol@google.com>, <linux-mm@kvack.org>, <lpieralisi@kernel.org>, <rananta@google.com>, <ryan.roberts@arm.com>, <david@redhat.com>, <linus.walleij@linaro.org>, <bhe@redhat.com> Cc: <aniketa@nvidia.com>, <cjia@nvidia.com>, <kwankhede@nvidia.com>, <targupta@nvidia.com>, <vsethi@nvidia.com>, <acurrid@nvidia.com>, <apopple@nvidia.com>, <jhubbard@nvidia.com>, <danw@nvidia.com>, <kvmarm@lists.linux.dev>, <mochs@nvidia.com>, <zhiw@nvidia.com>, <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org> Subject: [PATCH v7 2/4] mm: introduce new flag to indicate wc safe Date: Sun, 11 Feb 2024 23:17:03 +0530 [thread overview] Message-ID: <20240211174705.31992-3-ankita@nvidia.com> (raw) In-Reply-To: <20240211174705.31992-1-ankita@nvidia.com> From: Ankit Agrawal <ankita@nvidia.com> Generalizing S2 setting from DEVICE_nGnRE to NormalNc for non PCI devices may be problematic. E.g. GICv2 vCPU interface, which is effectively a shared peripheral, can allow a guest to affect another guest's interrupt distribution. The issue may be solved by limiting the relaxation to mappings that have a user VMA. Still there is insufficient information and uncertainity in the behavior of non PCI drivers. Add a new flag VM_ALLOW_ANY_UNCACHED to indicate KVM that the device is WC capable and these S2 changes can be extended to it. KVM can use this flag to activate the code. Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Ankit Agrawal <ankita@nvidia.com> --- include/linux/mm.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index f5a97dec5169..59576e56c58b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -391,6 +391,20 @@ extern unsigned int kobjsize(const void *objp); # define VM_UFFD_MINOR VM_NONE #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ +/* + * This flag is used to connect VFIO to arch specific KVM code. It + * indicates that the memory under this VMA is safe for use with any + * non-cachable memory type inside KVM. Some VFIO devices, on some + * platforms, are thought to be unsafe and can cause machine crashes + * if KVM does not lock down the memory type. + */ +#ifdef CONFIG_64BIT +#define VM_ALLOW_ANY_UNCACHED_BIT 39 +#define VM_ALLOW_ANY_UNCACHED BIT(VM_ALLOW_ANY_UNCACHED_BIT) +#else +#define VM_ALLOW_ANY_UNCACHED VM_NONE +#endif + /* Bits set in the VMA until the stack is in its final location */ #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY) -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: <ankita@nvidia.com> To: <ankita@nvidia.com>, <jgg@nvidia.com>, <maz@kernel.org>, <oliver.upton@linux.dev>, <james.morse@arm.com>, <suzuki.poulose@arm.com>, <yuzenghui@huawei.com>, <reinette.chatre@intel.com>, <surenb@google.com>, <stefanha@redhat.com>, <brauner@kernel.org>, <catalin.marinas@arm.com>, <will@kernel.org>, <mark.rutland@arm.com>, <alex.williamson@redhat.com>, <kevin.tian@intel.com>, <yi.l.liu@intel.com>, <ardb@kernel.org>, <akpm@linux-foundation.org>, <andreyknvl@gmail.com>, <wangjinchao@xfusion.com>, <gshan@redhat.com>, <shahuang@redhat.com>, <ricarkol@google.com>, <linux-mm@kvack.org>, <lpieralisi@kernel.org>, <rananta@google.com>, <ryan.roberts@arm.com>, <david@redhat.com>, <linus.walleij@linaro.org>, <bhe@redhat.com> Cc: <aniketa@nvidia.com>, <cjia@nvidia.com>, <kwankhede@nvidia.com>, <targupta@nvidia.com>, <vsethi@nvidia.com>, <acurrid@nvidia.com>, <apopple@nvidia.com>, <jhubbard@nvidia.com>, <danw@nvidia.com>, <kvmarm@lists.linux.dev>, <mochs@nvidia.com>, <zhiw@nvidia.com>, <kvm@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org> Subject: [PATCH v7 2/4] mm: introduce new flag to indicate wc safe Date: Sun, 11 Feb 2024 23:17:03 +0530 [thread overview] Message-ID: <20240211174705.31992-3-ankita@nvidia.com> (raw) In-Reply-To: <20240211174705.31992-1-ankita@nvidia.com> From: Ankit Agrawal <ankita@nvidia.com> Generalizing S2 setting from DEVICE_nGnRE to NormalNc for non PCI devices may be problematic. E.g. GICv2 vCPU interface, which is effectively a shared peripheral, can allow a guest to affect another guest's interrupt distribution. The issue may be solved by limiting the relaxation to mappings that have a user VMA. Still there is insufficient information and uncertainity in the behavior of non PCI drivers. Add a new flag VM_ALLOW_ANY_UNCACHED to indicate KVM that the device is WC capable and these S2 changes can be extended to it. KVM can use this flag to activate the code. Suggested-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Ankit Agrawal <ankita@nvidia.com> --- include/linux/mm.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index f5a97dec5169..59576e56c58b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -391,6 +391,20 @@ extern unsigned int kobjsize(const void *objp); # define VM_UFFD_MINOR VM_NONE #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ +/* + * This flag is used to connect VFIO to arch specific KVM code. It + * indicates that the memory under this VMA is safe for use with any + * non-cachable memory type inside KVM. Some VFIO devices, on some + * platforms, are thought to be unsafe and can cause machine crashes + * if KVM does not lock down the memory type. + */ +#ifdef CONFIG_64BIT +#define VM_ALLOW_ANY_UNCACHED_BIT 39 +#define VM_ALLOW_ANY_UNCACHED BIT(VM_ALLOW_ANY_UNCACHED_BIT) +#else +#define VM_ALLOW_ANY_UNCACHED VM_NONE +#endif + /* Bits set in the VMA until the stack is in its final location */ #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY) -- 2.34.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2024-02-11 17:47 UTC|newest] Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-02-11 17:47 [PATCH v7 0/4] kvm: arm64: allow the VM to select DEVICE_* and NORMAL_NC for IO memory ankita 2024-02-11 17:47 ` ankita 2024-02-11 17:47 ` [PATCH v7 1/4] kvm: arm64: introduce new flag for non-cacheable " ankita 2024-02-11 17:47 ` ankita 2024-02-11 17:47 ` ankita [this message] 2024-02-11 17:47 ` [PATCH v7 2/4] mm: introduce new flag to indicate wc safe ankita 2024-02-12 13:13 ` David Hildenbrand 2024-02-12 13:13 ` David Hildenbrand 2024-02-13 3:41 ` Ankit Agrawal 2024-02-13 3:41 ` Ankit Agrawal 2024-02-11 17:47 ` [PATCH v7 3/4] kvm: arm64: set io memory s2 pte as normalnc for vfio pci device ankita 2024-02-11 17:47 ` ankita 2024-02-11 17:47 ` [PATCH v7 4/4] vfio: convey kvm that the vfio-pci device is wc safe ankita 2024-02-11 17:47 ` ankita 2024-02-12 13:16 ` David Hildenbrand 2024-02-12 13:16 ` David Hildenbrand 2024-02-12 17:05 ` Alex Williamson 2024-02-12 17:05 ` Alex Williamson 2024-02-12 17:20 ` Jason Gunthorpe 2024-02-12 17:20 ` Jason Gunthorpe 2024-02-12 17:27 ` Alex Williamson 2024-02-12 17:27 ` Alex Williamson 2024-02-13 1:59 ` Ankit Agrawal 2024-02-13 1:59 ` Ankit Agrawal 2024-02-12 10:26 ` [PATCH v7 0/4] kvm: arm64: allow the VM to select DEVICE_* and NORMAL_NC for IO memory David Hildenbrand 2024-02-12 10:26 ` David Hildenbrand 2024-02-12 12:56 ` Jason Gunthorpe 2024-02-12 12:56 ` Jason Gunthorpe 2024-02-12 13:06 ` David Hildenbrand 2024-02-12 13:06 ` David Hildenbrand 2024-02-12 20:24 ` Oliver Upton 2024-02-12 20:24 ` Oliver Upton 2024-02-13 2:29 ` Ankit Agrawal 2024-02-13 2:29 ` Ankit Agrawal
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