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110 lines
3.6 KiB
110 lines
3.6 KiB
From 2fc8489b70445a3db0a2e72c1f1edb4d61d404d6 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= <clg@redhat.com>
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Date: Mon, 16 Jan 2023 18:46:05 +0100
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Subject: [PATCH] s390x/pv: Implement a CGS check helper
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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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RH-Author: Cédric Le Goater <clg@redhat.com>
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RH-MergeRequest: 271: Secure guest can't boot with maximal number of vcpus (248)
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RH-Bugzilla: 2187159
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Jon Maloy <jmaloy@redhat.com>
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RH-Commit: [1/1] c870d525c48ab6d0df964b5abe48efe2528c9883
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When a protected VM is started with the maximum number of CPUs (248),
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the service call providing information on the CPUs requires more
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buffer space than allocated and QEMU disgracefully aborts :
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LOADPARM=[........]
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Using virtio-blk.
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Using SCSI scheme.
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...................................................................................
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qemu-system-s390x: KVM_S390_MEM_OP failed: Argument list too long
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When protected virtualization is initialized, compute the maximum
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number of vCPUs supported by the machine and return useful information
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to the user before the machine starts in case of error.
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Suggested-by: Thomas Huth <thuth@redhat.com>
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Reviewed-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Cédric Le Goater <clg@redhat.com>
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Message-Id: <20230116174607.2459498-2-clg@kaod.org>
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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(cherry picked from commit 75d7150c636569f6687f7e70a33be893be43eb5f)
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Signed-off-by: Cédric Le Goater <clg@redhat.com>
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---
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hw/s390x/pv.c | 40 ++++++++++++++++++++++++++++++++++++++++
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1 file changed, 40 insertions(+)
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diff --git a/hw/s390x/pv.c b/hw/s390x/pv.c
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index 728ba24547..749e5db1ce 100644
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--- a/hw/s390x/pv.c
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+++ b/hw/s390x/pv.c
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@@ -20,6 +20,7 @@
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#include "exec/confidential-guest-support.h"
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#include "hw/s390x/ipl.h"
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#include "hw/s390x/pv.h"
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+#include "hw/s390x/sclp.h"
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#include "target/s390x/kvm/kvm_s390x.h"
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static bool info_valid;
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@@ -249,6 +250,41 @@ struct S390PVGuestClass {
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ConfidentialGuestSupportClass parent_class;
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};
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+/*
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+ * If protected virtualization is enabled, the amount of data that the
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+ * Read SCP Info Service Call can use is limited to one page. The
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+ * available space also depends on the Extended-Length SCCB (ELS)
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+ * feature which can take more buffer space to store feature
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+ * information. This impacts the maximum number of CPUs supported in
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+ * the machine.
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+ */
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+static uint32_t s390_pv_get_max_cpus(void)
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+{
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+ int offset_cpu = s390_has_feat(S390_FEAT_EXTENDED_LENGTH_SCCB) ?
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+ offsetof(ReadInfo, entries) : SCLP_READ_SCP_INFO_FIXED_CPU_OFFSET;
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+
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+ return (TARGET_PAGE_SIZE - offset_cpu) / sizeof(CPUEntry);
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+}
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+
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+static bool s390_pv_check_cpus(Error **errp)
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+{
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+ MachineState *ms = MACHINE(qdev_get_machine());
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+ uint32_t pv_max_cpus = s390_pv_get_max_cpus();
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+
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+ if (ms->smp.max_cpus > pv_max_cpus) {
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+ error_setg(errp, "Protected VMs support a maximum of %d CPUs",
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+ pv_max_cpus);
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+ return false;
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+ }
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+
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+ return true;
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+}
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+
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+static bool s390_pv_guest_check(ConfidentialGuestSupport *cgs, Error **errp)
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+{
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+ return s390_pv_check_cpus(errp);
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+}
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+
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int s390_pv_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
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{
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if (!object_dynamic_cast(OBJECT(cgs), TYPE_S390_PV_GUEST)) {
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@@ -261,6 +297,10 @@ int s390_pv_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
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return -1;
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}
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+ if (!s390_pv_guest_check(cgs, errp)) {
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+ return -1;
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+ }
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+
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cgs->ready = true;
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return 0;
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--
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2.39.1
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