On Mon, Oct 22, 2018 at 10:48:35AM +0530, Bharata B Rao wrote:
> A secure guest will share some of its pages with hypervisor (Eg. virtio
> bounce buffers etc). Support shared pages in HMM driver.
>
> Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_hv_hmm.c | 69 ++++++++++++++++++++++++++++++--
> 1 file changed, 65 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c b/arch/powerpc/kvm/book3s_hv_hmm.c
> index a2ee3163a312..09b8e19b7605 100644
> --- a/arch/powerpc/kvm/book3s_hv_hmm.c
> +++ b/arch/powerpc/kvm/book3s_hv_hmm.c
> @@ -50,6 +50,7 @@ struct kvmppc_hmm_page_pvt {
> struct hlist_head *hmm_hash;
> unsigned int lpid;
> unsigned long gpa;
> + bool skip_page_out;
> };
>
> struct kvmppc_hmm_migrate_args {
> @@ -278,6 +279,65 @@ static unsigned long kvmppc_gpa_to_hva(struct kvm *kvm, unsigned long gpa,
> return hva;
> }
>
> +/*
> + * Shares the page with HV, thus making it a normal page.
> + *
> + * - If the page is already secure, then provision a new page and share
> + * - If the page is a normal page, share the existing page
> + *
> + * In the former case, uses the HMM fault handler to release the HMM page.
> + */
> +static unsigned long
> +kvmppc_share_page(struct kvm *kvm, unsigned long gpa,
> + unsigned long addr, unsigned long page_shift)
> +{
> +
So this is a special flag passed via the hypercall to say
this page can be skipped from page_out from secure memory?
Who has the master copy of the page at this point?
In which case the question is
Why did we get a fault on the page which resulted in the
fault migration ops being called?
What category of pages are considered shared?
Balbir
