From dd8dc442c1e3b1798fad61211f3b090523dd926d Mon Sep 17 00:00:00 2001 From: "Fabio M. De Francesco" Date: Thu, 1 Sep 2022 15:57:14 +0200 Subject: [PATCH] misc/vmw_vmci: Use kmap_local_page() in vmci_queue_pair.c MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit kmap() is being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as the mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap’s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. Since its use in vmci_queue_pair.c is safe everywhere, replace kmap() with kmap_local_page(). Cc: "Venkataramanan, Anirudh" Suggested-by: Ira Weiny Signed-off-by: Fabio M. De Francesco Link: https://lore.kernel.org/r/20220901135714.16481-1-fmdefrancesco@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/vmw_vmci/vmci_queue_pair.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c b/drivers/misc/vmw_vmci/vmci_queue_pair.c index 8f2de18..e71068f 100644 --- a/drivers/misc/vmw_vmci/vmci_queue_pair.c +++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c @@ -324,7 +324,7 @@ static void *qp_alloc_queue(u64 size, u32 flags) /* * Copies from a given buffer or iovector to a VMCI Queue. Uses - * kmap()/kunmap() to dynamically map/unmap required portions of the queue + * kmap_local_page() to dynamically map required portions of the queue * by traversing the offset -> page translation structure for the queue. * Assumes that offset + size does not wrap around in the queue. */ @@ -345,7 +345,7 @@ static int qp_memcpy_to_queue_iter(struct vmci_queue *queue, size_t to_copy; if (kernel_if->host) - va = kmap(kernel_if->u.h.page[page_index]); + va = kmap_local_page(kernel_if->u.h.page[page_index]); else va = kernel_if->u.g.vas[page_index + 1]; /* Skip header. */ @@ -359,12 +359,12 @@ static int qp_memcpy_to_queue_iter(struct vmci_queue *queue, if (!copy_from_iter_full((u8 *)va + page_offset, to_copy, from)) { if (kernel_if->host) - kunmap(kernel_if->u.h.page[page_index]); + kunmap_local(va); return VMCI_ERROR_INVALID_ARGS; } bytes_copied += to_copy; if (kernel_if->host) - kunmap(kernel_if->u.h.page[page_index]); + kunmap_local(va); } return VMCI_SUCCESS; @@ -372,7 +372,7 @@ static int qp_memcpy_to_queue_iter(struct vmci_queue *queue, /* * Copies to a given buffer or iovector from a VMCI Queue. Uses - * kmap()/kunmap() to dynamically map/unmap required portions of the queue + * kmap_local_page() to dynamically map required portions of the queue * by traversing the offset -> page translation structure for the queue. * Assumes that offset + size does not wrap around in the queue. */ @@ -393,7 +393,7 @@ static int qp_memcpy_from_queue_iter(struct iov_iter *to, int err; if (kernel_if->host) - va = kmap(kernel_if->u.h.page[page_index]); + va = kmap_local_page(kernel_if->u.h.page[page_index]); else va = kernel_if->u.g.vas[page_index + 1]; /* Skip header. */ @@ -407,12 +407,12 @@ static int qp_memcpy_from_queue_iter(struct iov_iter *to, err = copy_to_iter((u8 *)va + page_offset, to_copy, to); if (err != to_copy) { if (kernel_if->host) - kunmap(kernel_if->u.h.page[page_index]); + kunmap_local(va); return VMCI_ERROR_INVALID_ARGS; } bytes_copied += to_copy; if (kernel_if->host) - kunmap(kernel_if->u.h.page[page_index]); + kunmap_local(va); } return VMCI_SUCCESS; -- 2.7.4