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From 03cf4bcbcfa55297b2359875640819a755b7860c Mon Sep 17 00:00:00 2001
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Message-Id: <03cf4bcbcfa55297b2359875640819a755b7860c@dist-git>
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From: Erik Skultety <eskultet@redhat.com>
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Date: Fri, 1 Feb 2019 17:21:55 +0100
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Subject: [PATCH] qemu: cgroup: Expose /dev/sev/ only to domains that require
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 SEV
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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SEV has a limit on number of concurrent guests. From security POV we
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should only expose resources (any resources for that matter) to domains
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that truly need them.
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Signed-off-by: Erik Skultety <eskultet@redhat.com>
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Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
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(cherry picked from commit a404ac34768e975bd420d1eeac3811563da67e3f)
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https: //bugzilla.redhat.com/show_bug.cgi?id=1665400
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Signed-off-by: Erik Skultety <eskultet@redhat.com>
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Reviewed-by: Ján Tomko <jtomko@redhat.com>
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---
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 src/qemu/qemu_cgroup.c | 19 +++++++++++++++++++
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 1 file changed, 19 insertions(+)
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diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
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index fd54333fb9..9f2fc1b062 100644
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--- a/src/qemu/qemu_cgroup.c
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+++ b/src/qemu/qemu_cgroup.c
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@@ -695,6 +695,22 @@ qemuTeardownChardevCgroup(virDomainObjPtr vm,
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 }
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+static int
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+qemuSetupSEVCgroup(virDomainObjPtr vm)
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+{
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+    qemuDomainObjPrivatePtr priv = vm->privateData;
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+    int ret;
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+
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+    if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_DEVICES))
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+        return 0;
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+
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+    ret = virCgroupAllowDevicePath(priv->cgroup, "/dev/sev",
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+                                   VIR_CGROUP_DEVICE_RW, false);
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+    virDomainAuditCgroupPath(vm, priv->cgroup, "allow", "/dev/sev",
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+                             "rw", ret);
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+    return ret;
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+}
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+
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 static int
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 qemuSetupDevicesCgroup(virDomainObjPtr vm)
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 {
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@@ -802,6 +818,9 @@ qemuSetupDevicesCgroup(virDomainObjPtr vm)
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             goto cleanup;
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     }
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+    if (vm->def->sev && qemuSetupSEVCgroup(vm) < 0)
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+        goto cleanup;
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+
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     ret = 0;
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  cleanup:
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     virObjectUnref(cfg);
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-- 
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2.20.1
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