On 24.10.19 13:40, Janosch Frank wrote:
> From: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
>
> Pin the guest pages when they are first accessed, instead of all at
> the same time when starting the guest.
>
> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
[...]
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 80aecd5bea9e..383e660e2221 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -15,8 +15,35 @@
> #include <asm/mman.h>
> #include "kvm-s390.h"
>
> +static void unpin_destroy(struct page **pages, int nr)
> +{
> + int i;
> + struct page *page;
> + u8 *val;
> +
> + for (i = 0; i < nr; i++) {
> + page = pages[i];
> + if (!page) /* page was never used */
> + continue;
> + val = (void *)page_to_phys(page);
Why dont we call the convert from secure directly here to avoid the fault overhead?
> + READ_ONCE(*val);
> + put_page(page);
as we also do the export here (via implicit reading that page) this can take a while.
I think we must add a cond_resched here.
> + }
> +}
> +
[...]
> -
> mutex_unlock(&kvm->slots_lock);
> +
> + kvm->arch.gmap->pinned_pages = vzalloc(npages * sizeof(struct page *));
> + if (!kvm->arch.gmap->pinned_pages)
> + goto out_err;
> kvm->arch.pv.guest_len = npages * PAGE_SIZE;
>
> /* Allocate variable storage */
> vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
> vlen += uv_info.guest_virt_base_stor_len;
> kvm->arch.pv.stor_var = vzalloc(vlen);
> - if (!kvm->arch.pv.stor_var) {
> - kvm_s390_pv_dealloc_vm(kvm);
> - return -ENOMEM;
> - }
> + if (!kvm->arch.pv.stor_var)
> + goto out_err;
> return 0;
> +
> +out_err:
> + kvm_s390_pv_dealloc_vm(kvm);
> + return -ENOMEM;
> }
>
> int kvm_s390_pv_destroy_vm(struct kvm *kvm)
> @@ -216,6 +246,11 @@ int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
> for (i = 0; i < size / PAGE_SIZE; i++) {
> uvcb.gaddr = addr + i * PAGE_SIZE;
> uvcb.tweak[1] = i * PAGE_SIZE;
> + down_read(&kvm->mm->mmap_sem);
> + rc = kvm_s390_pv_pin_page(kvm->arch.gmap, uvcb.gaddr);
> + up_read(&kvm->mm->mmap_sem);
Here we should also have a cond_resched();
> + if (rc && (rc != -EEXIST))
> + break;
> retry:
> rc = uv_call(0, (u64)&uvcb);
> if (!rc)
>
