From 1e9877902dc7e11d2be038371c6fbf2dfcd469d7 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 12 Feb 2016 13:01:54 -0800 Subject: mm/gup: Introduce get_user_pages_remote() For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Kirill A. Shutemov Cc: Linus Torvalds Cc: Naoya Horiguchi Cc: Peter Zijlstra Cc: Rik van Riel Cc: Srikar Dronamraju Cc: Vlastimil Babka Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- virt/kvm/async_pf.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'virt/kvm') diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 353159922456..d604e87a510a 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -79,7 +79,13 @@ static void async_pf_execute(struct work_struct *work) might_sleep(); - get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL); + /* + * This work is run asynchromously to the task which owns + * mm and might be done in another context, so we must + * use FOLL_REMOTE. + */ + __get_user_pages_unlocked(NULL, mm, addr, 1, 1, 0, NULL, FOLL_REMOTE); + kvm_async_page_present_sync(vcpu, apf); spin_lock(&vcpu->async_pf.lock); -- cgit v1.2.3 From d4edcf0d56958db0aca0196314ca38a5e730ea92 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 12 Feb 2016 13:01:56 -0800 Subject: mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm We will soon modify the vanilla get_user_pages() so it can no longer be used on mm/tasks other than 'current/current->mm', which is by far the most common way it is called. For now, we allow the old-style calls, but warn when they are used. (implemented in previous patch) This patch switches all callers of: get_user_pages() get_user_pages_unlocked() get_user_pages_locked() to stop passing tsk/mm so they will no longer see the warnings. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Kirill A. Shutemov Cc: Linus Torvalds Cc: Naoya Horiguchi Cc: Peter Zijlstra Cc: Rik van Riel Cc: Srikar Dronamraju Cc: Vlastimil Babka Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210156.113E9407@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- virt/kvm/kvm_main.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'virt/kvm') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a11cfd20a6a0..0253ad900ec3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1264,15 +1264,16 @@ unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *w return gfn_to_hva_memslot_prot(slot, gfn, writable); } -static int get_user_page_nowait(struct task_struct *tsk, struct mm_struct *mm, - unsigned long start, int write, struct page **page) +static int get_user_page_nowait(unsigned long start, int write, + struct page **page) { int flags = FOLL_TOUCH | FOLL_NOWAIT | FOLL_HWPOISON | FOLL_GET; if (write) flags |= FOLL_WRITE; - return __get_user_pages(tsk, mm, start, 1, flags, page, NULL, NULL); + return __get_user_pages(current, current->mm, start, 1, flags, page, + NULL, NULL); } static inline int check_user_page_hwpoison(unsigned long addr) @@ -1334,8 +1335,7 @@ static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, if (async) { down_read(¤t->mm->mmap_sem); - npages = get_user_page_nowait(current, current->mm, - addr, write_fault, page); + npages = get_user_page_nowait(addr, write_fault, page); up_read(¤t->mm->mmap_sem); } else npages = __get_user_pages_unlocked(current, current->mm, addr, 1, -- cgit v1.2.3