Re: [PATCH v4 20/36] KVM: s390/mm: handle guest unpin events

Cornelia Huck
2020-02-25T12:19:04Z

On Mon, 24 Feb 2020 06:40:51 -0500
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: Claudio Imbrenda <imbrenda@linux.ibm.com>
>
> The current code tries to first pin shared pages, if that fails (e.g.
> because the page is not shared) it will export them. For shared pages
> this means that we get a new intercept telling us that the guest is
> unsharing that page. We will make the page secure at that point in time
> and revoke the host access. This is synchronized with other host events,
> e.g. the code will wait until host I/O has finished.
>
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> [borntraeger@de.ibm.com: patch merging, splitting, fixing]
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/kvm/intercept.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
> index b6b7d4b0e26c..c06599939541 100644
> --- a/arch/s390/kvm/intercept.c
> +++ b/arch/s390/kvm/intercept.c
> @@ -16,6 +16,7 @@
> #include <asm/asm-offsets.h>
> #include <asm/irq.h>
> #include <asm/sysinfo.h>
> +#include <asm/uv.h>
>
> #include "kvm-s390.h"
> #include "gaccess.h"
> @@ -484,12 +485,35 @@ static int handle_pv_sclp(struct kvm_vcpu *vcpu)
> return 0;
> }
>
> +static int handle_pv_uvc(struct kvm_vcpu *vcpu)
> +{
> + struct uv_cb_share *guest_uvcb = (void *)vcpu->arch.sie_block->sidad;
> + struct uv_cb_cts uvcb = {
> + .header.cmd = UVC_CMD_UNPIN_PAGE_SHARED,
> + .header.len = sizeof(uvcb),
> + .guest_handle = kvm_s390_pv_get_handle(vcpu->kvm),
> + .gaddr = guest_uvcb->paddr,
> + };
> + int rc;
> +
> + if (guest_uvcb->header.cmd != UVC_CMD_REMOVE_SHARED_ACCESS) {
> + WARN_ONCE(1, "Unexpected UVC 0x%x!\n", guest_uvcb->header.cmd);

"Unexpected notification intercept for UVC 0x%x"

?

> + return 0;
> + }
> + rc = gmap_make_secure(vcpu->arch.gmap, uvcb.gaddr, &uvcb);
> + if (rc == -EINVAL)

Add a comment why?

> + return 0;
> + return rc;
> +}
> +
> static int handle_pv_notification(struct kvm_vcpu *vcpu)
> {
> if (vcpu->arch.sie_block->ipa == 0xb210)
> return handle_pv_spx(vcpu);
> if (vcpu->arch.sie_block->ipa == 0xb220)
> return handle_pv_sclp(vcpu);
> + if (vcpu->arch.sie_block->ipa == 0xb9a4)
> + return handle_pv_uvc(vcpu);
>
> return handle_instruction(vcpu);
> }