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SubjectRe: [PATCH] kvm: allow RO page when atomic && !write_fault
On Mon, Feb 21, 2011 at 11:47:36AM +0800, Lai Jiangshan wrote:
>
> Atomic-able hva_to_pfn() patches and allow-read-only-page patches
> are merged almost the same time. But hva_to_pfn() does not handle
> these two issues well together.
>
> When @atomic && !@write_fault && host-is-read-only-page-mapped
> the code will return fault_page, actually, it will be better
> if we return the pfn of the read-only-page.
>
This patch will conflict with not yet applied https://lkml.org/lkml/2011/2/1/94
What it the status of that patch?

> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 1fa0d29..f49cfc0 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1060,31 +1060,27 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
> BUG_ON(!write_fault && !writable);
>
> if (writable)
> - *writable = true;
> + *writable = write_fault;
>
> if (atomic || async)
> - npages = __get_user_pages_fast(addr, 1, 1, page);
> + npages = __get_user_pages_fast(addr, 1, write_fault, page);
>
> if (unlikely(npages != 1) && !atomic) {
> might_sleep();
> -
> - if (writable)
> - *writable = write_fault;
> -
> npages = get_user_pages_fast(addr, 1, write_fault, page);
> + }
>
> - /* map read fault as writable if possible */
> - if (unlikely(!write_fault) && npages == 1) {
> - struct page *wpage[1];
> + /* map read fault as writable if possible */
> + if (unlikely(!write_fault) && npages == 1) {
> + struct page *wpage[1];
>
> - npages = __get_user_pages_fast(addr, 1, 1, wpage);
> - if (npages == 1) {
> - *writable = true;
> - put_page(page[0]);
> - page[0] = wpage[0];
> - }
> - npages = 1;
> + npages = __get_user_pages_fast(addr, 1, 1, wpage);
> + if (npages == 1) {
> + *writable = true;
> + put_page(page[0]);
> + page[0] = wpage[0];
> }
> + npages = 1;
> }
>
> if (unlikely(npages != 1)) {
> --
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--
Gleb.


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