Re: [PATCH v3 04/10] KVM: Implement kvm_put_guest()
From: Jonathan Cameron <jonathan.cameron@huawei.com>
Date: 2019-08-22 10:29:56
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kvm, kvmarm, linux-doc, lkml
On Wed, 21 Aug 2019 16:36:50 +0100 Steven Price [off-list ref] wrote:
quoted hunk ↗ jump to hunk
kvm_put_guest() is analogous to put_user() - it writes a single value to the guest physical address. The implementation is built upon put_user() and so it has the same single copy atomic properties. Signed-off-by: Steven Price <steven.price@arm.com> --- include/linux/kvm_host.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index fcb46b3374c6..e154a1897e20 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h@@ -746,6 +746,30 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, unsigned long len); int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc, gpa_t gpa, unsigned long len); + +#define __kvm_put_guest(kvm, gfn, offset, value, type) \ +({ \ + unsigned long __addr = gfn_to_hva(kvm, gfn); \ + type __user *__uaddr = (type __user *)(__addr + offset); \ + int __ret = 0; \
Why initialize __ret?
+ \
+ if (kvm_is_error_hva(__addr)) \
+ __ret = -EFAULT; \
+ else \
+ __ret = put_user(value, __uaddr); \
+ if (!__ret) \
+ mark_page_dirty(kvm, gfn); \
+ __ret; \
+})
+
+#define kvm_put_guest(kvm, gpa, value, type) \
+({ \
+ gpa_t __gpa = gpa; \
+ struct kvm *__kvm = kvm; \
+ __kvm_put_guest(__kvm, __gpa >> PAGE_SHIFT, \
+ offset_in_page(__gpa), (value), type); \
+})
+
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);_______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel