linux-kernel - [PATCH v4 2/2] s390: virtio: PV needs VIRTIO I/O device protection

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Date:   Tue,  7 Jul 2020 10:44:37 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     pasic@...ux.ibm.com, borntraeger@...ibm.com, frankja@...ux.ibm.com,
        mst@...hat.com, jasowang@...hat.com, cohuck@...hat.com,
        kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, thomas.lendacky@....com,
        david@...son.dropbear.id.au, linuxram@...ibm.com,
        heiko.carstens@...ibm.com, gor@...ux.ibm.com
Subject: [PATCH v4 2/2] s390: virtio: PV needs VIRTIO I/O device protection

S390, protecting the guest memory against unauthorized host access
needs to enforce VIRTIO I/O device protection through the use of
VIRTIO_F_VERSION_1 and VIRTIO_F_IOMMU_PLATFORM.

Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
---
 arch/s390/kernel/uv.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index c296e5c8dbf9..106330f6eda1 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -14,6 +14,7 @@
 #include <linux/memblock.h>
 #include <linux/pagemap.h>
 #include <linux/swap.h>
+#include <linux/virtio_config.h>
 #include <asm/facility.h>
 #include <asm/sections.h>
 #include <asm/uv.h>
@@ -413,3 +414,27 @@ static int __init uv_info_init(void)
 }
 device_initcall(uv_info_init);
 #endif
+
+/*
+ * arch_validate_virtio_iommu_platform
+ * @dev: the VIRTIO device being added
+ *
+ * Return value: returns -ENODEV if any features of the
+ *               device breaks the protected virtualization
+ *               0 otherwise.
+ */
+int arch_validate_virtio_features(struct virtio_device *dev)
+{
+	if (!virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
+		dev_warn(&dev->dev, "device must provide VIRTIO_F_VERSION_1\n");
+		return is_prot_virt_guest() ? -ENODEV : 0;
+	}
+
+	if (!virtio_has_feature(dev, VIRTIO_F_IOMMU_PLATFORM)) {
+		dev_warn(&dev->dev,
+			 "device must provide VIRTIO_F_IOMMU_PLATFORM\n");
+		return is_prot_virt_guest() ? -ENODEV : 0;
+	}
+
+	return 0;
+}
-- 
2.25.1