x86/intel_rdt: Fix unchecked MSR access

rchatre · KAGA-KOKO · commit 70479c012b67 · 2018-09-18T23:38:06.000+02:00
When a new resource group is created, it is initialized with sane defaults that currently assume the resource being initialized is a CAT resource. This code path is also followed by a MBA resource that is not allocated the same as a CAT resource and as a result we encounter the following unchecked MSR access error: unchecked MSR access error: WRMSR to 0xd51 (tried to write 0x0000 000000000064) at rIP: 0xffffffffae059994 (native_write_msr+0x4/0x20) Call Trace: mba_wrmsr+0x41/0x80 update_domains+0x125/0x130 rdtgroup_mkdir+0x270/0x500 Fix the above by ensuring the initial allocation is only attempted on a CAT resource. Fixes: 95f0b77 ("x86/intel_rdt: Initialize new resource group with sane defaults") Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: "H Peter Anvin" <hpa@zytor.com> Cc: "Tony Luck" <tony.luck@intel.com> Cc: "Xiaochen Shen" <xiaochen.shen@intel.com> Cc: "Chen Yu" <yu.c.chen@intel.com> Link: https://lkml.kernel.org/r/1537048707-76280-6-git-send-email-fenghua.yu@intel.com
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -2349,6 +2349,12 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 	u32 *ctrl;
 
 	for_each_alloc_enabled_rdt_resource(r) {
+		/*
+		 * Only initialize default allocations for CBM cache
+		 * resources
+		 */
+		if (r->rid == RDT_RESOURCE_MBA)
+			continue;
 		list_for_each_entry(d, &r->domains, list) {
 			d->have_new_ctrl = false;
 			d->new_ctrl = r->cache.shareable_bits;
@@ -2386,6 +2392,12 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 	}
 
 	for_each_alloc_enabled_rdt_resource(r) {
+		/*
+		 * Only initialize default allocations for CBM cache
+		 * resources
+		 */
+		if (r->rid == RDT_RESOURCE_MBA)
+			continue;
 		ret = update_domains(r, rdtgrp->closid);
 		if (ret < 0) {
 			rdt_last_cmd_puts("failed to initialize allocations\n");
