From f88fb1335733029b4630fb93cfaad349a81e57b2 Mon Sep 17 00:00:00 2001 From: Tony Krowiak Date: Tue, 15 Aug 2023 14:43:33 -0400 Subject: [PATCH] s390/vfio-ap: make sure nib is shared Since the NIB is visible by HW, KVM and the (PV) guest it needs to be in non-secure or secure but shared storage. Return code 6 is used to indicate to a PV guest that its NIB would be on secure, unshared storage and therefore the NIB address is invalid. Unfortunately we have no easy way to check if a page is unshared after vfio_pin_pages() since it will automatically export an unshared page if the UV pin shared call did not succeed due to a page being in unshared state. Therefore we use the fact that UV pinning it a second time is a nop but trying to pin an exported page is an error (0x102). If we encounter this error, we do a vfio unpin and import the page again, since vfio_pin_pages() exported it. Signed-off-by: Janosch Frank Signed-off-by: Tony Krowiak Acked-by: Halil Pasic Tested-by: Viktor Mihajlovski Link: https://lore.kernel.org/r/20230815184333.6554-13-akrowiak@linux.ibm.com Signed-off-by: Heiko Carstens --- drivers/s390/crypto/vfio_ap_ops.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index 8bda52c..0509f80 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -359,6 +359,28 @@ static int vfio_ap_validate_nib(struct kvm_vcpu *vcpu, dma_addr_t *nib) return 0; } +static int ensure_nib_shared(unsigned long addr, struct gmap *gmap) +{ + int ret; + + /* + * The nib has to be located in shared storage since guest and + * host access it. vfio_pin_pages() will do a pin shared and + * if that fails (possibly because it's not a shared page) it + * calls export. We try to do a second pin shared here so that + * the UV gives us an error code if we try to pin a non-shared + * page. + * + * If the page is already pinned shared the UV will return a success. + */ + ret = uv_pin_shared(addr); + if (ret) { + /* vfio_pin_pages() likely exported the page so let's re-import */ + gmap_convert_to_secure(gmap, addr); + } + return ret; +} + /** * vfio_ap_irq_enable - Enable Interruption for a APQN * @@ -422,6 +444,14 @@ static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q, h_nib = page_to_phys(h_page) | (nib & ~PAGE_MASK); aqic_gisa.gisc = isc; + /* NIB in non-shared storage is a rc 6 for PV guests */ + if (kvm_s390_pv_cpu_is_protected(vcpu) && + ensure_nib_shared(h_nib & PAGE_MASK, kvm->arch.gmap)) { + vfio_unpin_pages(&q->matrix_mdev->vdev, nib, 1); + status.response_code = AP_RESPONSE_INVALID_ADDRESS; + return status; + } + nisc = kvm_s390_gisc_register(kvm, isc); if (nisc < 0) { VFIO_AP_DBF_WARN("%s: gisc registration failed: nisc=%d, isc=%d, apqn=%#04x\n", -- 2.7.4