From d5ebde1e2b46154d7e03efb1ae3039a304e5386d Mon Sep 17 00:00:00 2001 From: Li kunyu Date: Wed, 28 Sep 2022 14:40:46 +0800 Subject: hyperv: simplify and rename generate_guest_id The generate_guest_id function is more suitable for use after the following modifications. 1. The return value of the function is modified to u64. 2. Remove the d_info1 and d_info2 parameters from the function, keep the u64 type kernel_version parameter. 3. Rename the function to make it clearly a Hyper-V related function, and modify it to hv_generate_guest_id. Signed-off-by: Li kunyu Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20220928064046.3545-1-kunyu@nfschina.com Signed-off-by: Wei Liu --- arch/x86/hyperv/hv_init.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 3de6d8b53367..032d85ac33fa 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -426,7 +426,7 @@ void __init hyperv_init(void) * 1. Register the guest ID * 2. Enable the hypercall and register the hypercall page */ - guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0); + guest_id = hv_generate_guest_id(LINUX_VERSION_CODE); wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id); /* Hyper-V requires to write guest os id via ghcb in SNP IVM. */ -- cgit v1.2.3 From 154fb14df7a3c81dea82eca7c0c46590f5ffc3d2 Mon Sep 17 00:00:00 2001 From: Zhao Liu Date: Wed, 28 Sep 2022 17:56:40 +0800 Subject: x86/hyperv: Replace kmap() with kmap_local_page() kmap() is being deprecated in favor of kmap_local_page()[1]. There are two main problems with kmap(): (1) It comes with an overhead as 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 are still valid. In the fuction hyperv_init() of hyperv/hv_init.c, the mapping is used in a single thread and is short live. So, in this case, it's safe to simply use kmap_local_page() to create mapping, and this avoids the wasted cost of kmap() for global synchronization. In addtion, the fuction hyperv_init() checks if kmap() fails by BUG_ON(). From the original discussion[2], the BUG_ON() here is just used to explicitly panic NULL pointer. So still keep the BUG_ON() in place to check if kmap_local_page() fails. Based on this consideration, memcpy_to_page() is not selected here but only kmap_local_page() is used. Therefore, replace kmap() with kmap_local_page() in hyperv/hv_init.c. [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com [2]: https://lore.kernel.org/lkml/20200915103710.cqmdvzh5lys4wsqo@liuwe-devbox-debian-v2/ Suggested-by: Dave Hansen Suggested-by: Ira Weiny Suggested-by: Fabio M. De Francesco Signed-off-by: Zhao Liu Link: https://lore.kernel.org/r/20220928095640.626350-1-zhao1.liu@linux.intel.com Signed-off-by: Wei Liu --- arch/x86/hyperv/hv_init.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 032d85ac33fa..29774126e931 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -459,13 +459,13 @@ void __init hyperv_init(void) wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); pg = vmalloc_to_page(hv_hypercall_pg); - dst = kmap(pg); + dst = kmap_local_page(pg); src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE, MEMREMAP_WB); BUG_ON(!(src && dst)); memcpy(dst, src, HV_HYP_PAGE_SIZE); memunmap(src); - kunmap(pg); + kunmap_local(dst); } else { hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg); wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64); -- cgit v1.2.3