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    Subject[PATCH v3 6/11] KVM: MMU: introduce gfn_to_pfn_atomic() function
    Introduce gfn_to_pfn_atomic(), it's the fast path and can used in atomic
    context, the later patch will use it

    Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
    ---
    arch/x86/mm/gup.c | 2 ++
    include/linux/kvm_host.h | 1 +
    virt/kvm/kvm_main.c | 32 +++++++++++++++++++++++++-------
    3 files changed, 28 insertions(+), 7 deletions(-)

    diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
    index 738e659..0c9034b 100644
    --- a/arch/x86/mm/gup.c
    +++ b/arch/x86/mm/gup.c
    @@ -6,6 +6,7 @@
    */
    #include <linux/sched.h>
    #include <linux/mm.h>
    +#include <linux/module.h>
    #include <linux/vmstat.h>
    #include <linux/highmem.h>

    @@ -274,6 +275,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,

    return nr;
    }
    +EXPORT_SYMBOL_GPL(__get_user_pages_fast);

    /**
    * get_user_pages_fast() - pin user pages in memory
    diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    index 9289d1a..515fefd 100644
    --- a/include/linux/kvm_host.h
    +++ b/include/linux/kvm_host.h
    @@ -295,6 +295,7 @@ void kvm_release_page_dirty(struct page *page);
    void kvm_set_page_dirty(struct page *page);
    void kvm_set_page_accessed(struct page *page);

    +pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
    pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
    pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
    struct kvm_memory_slot *slot, gfn_t gfn);
    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 885d3f5..60bb3d5 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -924,19 +924,25 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
    }
    EXPORT_SYMBOL_GPL(gfn_to_hva);

    -static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
    +static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic)
    {
    struct page *page[1];
    int npages;
    pfn_t pfn;

    - might_sleep();
    -
    - npages = get_user_pages_fast(addr, 1, 1, page);
    + if (atomic)
    + npages = __get_user_pages_fast(addr, 1, 1, page);
    + else {
    + might_sleep();
    + npages = get_user_pages_fast(addr, 1, 1, page);
    + }

    if (unlikely(npages != 1)) {
    struct vm_area_struct *vma;

    + if (atomic)
    + goto return_bad_page;
    +
    down_read(&current->mm->mmap_sem);
    if (is_hwpoison_address(addr)) {
    up_read(&current->mm->mmap_sem);
    @@ -949,6 +955,7 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
    if (vma == NULL || addr < vma->vm_start ||
    !(vma->vm_flags & VM_PFNMAP)) {
    up_read(&current->mm->mmap_sem);
    +return_bad_page:
    get_page(bad_page);
    return page_to_pfn(bad_page);
    }
    @@ -962,7 +969,7 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
    return pfn;
    }

    -pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
    +pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic)
    {
    unsigned long addr;

    @@ -972,7 +979,18 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
    return page_to_pfn(bad_page);
    }

    - return hva_to_pfn(kvm, addr);
    + return hva_to_pfn(kvm, addr, atomic);
    +}
    +
    +pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
    +{
    + return __gfn_to_pfn(kvm, gfn, true);
    +}
    +EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
    +
    +pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
    +{
    + return __gfn_to_pfn(kvm, gfn, false);
    }
    EXPORT_SYMBOL_GPL(gfn_to_pfn);

    @@ -980,7 +998,7 @@ pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
    struct kvm_memory_slot *slot, gfn_t gfn)
    {
    unsigned long addr = gfn_to_hva_memslot(slot, gfn);
    - return hva_to_pfn(kvm, addr);
    + return hva_to_pfn(kvm, addr, false);
    }

    struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
    --
    1.6.1.2



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