[PATCH 3/5] xen/domain: Audit config->max_vcpus during {, arch_}check_domain_config()

[Andrew Cooper <andrew.cooper3@citrix.com>]

The purpose of this is to move the auduting to be earlier than
arch_domain_create().

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>

The max_vcpus setting for GIC_V3 is somewhat confusing.  The current GIC_V3
driver claims to support 4096 cpus, while the newer GIC_V3 driver uses 255.
In both cases, this gets clipped to 128 or 8 by the MAX_VIRT_CPUS setting.
---
 xen/arch/arm/domain.c | 18 ++++++++++++++++++
 xen/arch/x86/domain.c |  6 ++++++
 xen/common/domain.c   |  3 +++
 3 files changed, 27 insertions(+)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 43593a4..9676893 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -601,6 +601,8 @@ void vcpu_switch_to_aarch64_mode(struct vcpu *v)
 
 int arch_check_domain_config(struct xen_domctl_createdomain *config)
 {
+    unsigned int max_vcpus = 0;
+
     /* Fill in the native GIC version, passed back to the toolstack. */
     if ( config->arch.gic_version == XEN_DOMCTL_CONFIG_GIC_NATIVE )
     {
@@ -619,6 +621,22 @@ int arch_check_domain_config(struct xen_domctl_createdomain *config)
         }
     }
 
+    /* Calculate the maximum number of vcpus from the selected GIC version... */
+    switch ( config->arch.gic_version )
+    {
+    case GIC_V2: max_vcpus = 8;   break;
+    case GIC_V3: max_vcpus = 255; break;
+
+    default:
+        return -EOPNOTSUPP;
+    }
+
+    /* ... clipped at the maximum value Xen has been configured for. */
+    max_vcpus = min(max_vcpus, MAX_VIRT_CPUS + 0u);
+
+    if ( config->max_vcpus > max_vcpus )
+        return -EINVAL;
+
     return 0;
 }
 
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 26cab7c..19023d4 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -403,6 +403,12 @@ void arch_vcpu_destroy(struct vcpu *v)
 
 int arch_check_domain_config(struct xen_domctl_createdomain *config)
 {
+    unsigned int max_vcpus = ((config->flags & XEN_DOMCTL_CDF_hvm_guest)
+                              ? HVM_MAX_VCPUS : MAX_VIRT_CPUS);
+
+    if ( config->max_vcpus > max_vcpus )
+        return -EINVAL;
+
     return 0;
 }
 
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 236c2ad..9882550 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -297,6 +297,9 @@ static int check_domain_config(struct xen_domctl_createdomain *config)
                            XEN_DOMCTL_CDF_xs_domain) )
         return -EINVAL;
 
+    if ( config->max_vcpus < 1 )
+        return -EINVAL;
+
     return arch_check_domain_config(config);
 }
 
-- 
2.1.4


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