x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h

[ Upstream commit c49a0a80137c7ca7d6ced4c812c9e07a949f6f24 ]

There have been reports of RDRAND issues after resuming from suspend on
some AMD family 15h and family 16h systems. This issue stems from a BIOS
not performing the proper steps during resume to ensure RDRAND continues
to function properly.

RDRAND support is indicated by CPUID Fn00000001_ECX[30]. This bit can be
reset by clearing MSR C001_1004[62]. Any software that checks for RDRAND
support using CPUID, including the kernel, will believe that RDRAND is
not supported.

Update the CPU initialization to clear the RDRAND CPUID bit for any family
15h and 16h processor that supports RDRAND. If it is known that the family
15h or family 16h system does not have an RDRAND resume issue or that the
system will not be placed in suspend, the "rdrand=force" kernel parameter
can be used to stop the clearing of the RDRAND CPUID bit.

Additionally, update the suspend and resume path to save and restore the
MSR C001_1004 value to ensure that the RDRAND CPUID setting remains in
place after resuming from suspend.

Note, that clearing the RDRAND CPUID bit does not prevent a processor
that normally supports the RDRAND instruction from executing it. So any
code that determined the support based on family and model won't #UD.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chen Yu <yu.c.chen@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Cc: "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: <stable@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "x86@kernel.org" <x86@kernel.org>
Link: https://lkml.kernel.org/r/7543af91666f491547bd86cebb1e17c66824ab9f.1566229943.git.thomas.lendacky@amd.com
[sl: adjust context in docs]
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 73 insertions, 13 deletions

diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index d5f64996394a..2e5052b2d238 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -12,6 +12,7 @@
 #include <linux/export.h>
 #include <linux/smp.h>
 #include <linux/perf_event.h>
+#include <linux/dmi.h>
 
 #include <asm/pgtable.h>
 #include <asm/proto.h>
@@ -23,7 +24,7 @@
 #include <asm/debugreg.h>
 #include <asm/cpu.h>
 #include <asm/mmu_context.h>
-#include <linux/dmi.h>
+#include <asm/cpu_device_id.h>
 
 #ifdef CONFIG_X86_32
 __visible unsigned long saved_context_ebx;
@@ -347,15 +348,14 @@ static int __init bsp_pm_check_init(void)
 
 core_initcall(bsp_pm_check_init);
 
-static int msr_init_context(const u32 *msr_id, const int total_num)
+static int msr_build_context(const u32 *msr_id, const int num)
 {
-	int i = 0;
+	struct saved_msrs *saved_msrs = &saved_context.saved_msrs;
 	struct saved_msr *msr_array;
+	int total_num;
+	int i, j;
 
-	if (saved_context.saved_msrs.array || saved_context.saved_msrs.num > 0) {
-		pr_err("x86/pm: MSR quirk already applied, please check your DMI match table.\n");
-		return -EINVAL;
-	}
+	total_num = saved_msrs->num + num;
 
 	msr_array = kmalloc_array(total_num, sizeof(struct saved_msr), GFP_KERNEL);
 	if (!msr_array) {
@@ -363,19 +363,30 @@ static int msr_init_context(const u32 *msr_id, const int total_num)
 		return -ENOMEM;
 	}
 
-	for (i = 0; i < total_num; i++) {
-		msr_array[i].info.msr_no	= msr_id[i];
+	if (saved_msrs->array) {
+		/*
+		 * Multiple callbacks can invoke this function, so copy any
+		 * MSR save requests from previous invocations.
+		 */
+		memcpy(msr_array, saved_msrs->array,
+		       sizeof(struct saved_msr) * saved_msrs->num);
+
+		kfree(saved_msrs->array);
+	}
+
+	for (i = saved_msrs->num, j = 0; i < total_num; i++, j++) {
+		msr_array[i].info.msr_no	= msr_id[j];
 		msr_array[i].valid		= false;
 		msr_array[i].info.reg.q		= 0;
 	}
-	saved_context.saved_msrs.num	= total_num;
-	saved_context.saved_msrs.array	= msr_array;
+	saved_msrs->num   = total_num;
+	saved_msrs->array = msr_array;
 
 	return 0;
 }
 
 /*
- * The following section is a quirk framework for problematic BIOSen:
+ * The following sections are a quirk framework for problematic BIOSen:
  * Sometimes MSRs are modified by the BIOSen after suspended to
  * RAM, this might cause unexpected behavior after wakeup.
  * Thus we save/restore these specified MSRs across suspend/resume
@@ -390,7 +401,7 @@ static int msr_initialize_bdw(const struct dmi_system_id *d)
 	u32 bdw_msr_id[] = { MSR_IA32_THERM_CONTROL };
 
 	pr_info("x86/pm: %s detected, MSR saving is needed during suspending.\n", d->ident);
-	return msr_init_context(bdw_msr_id, ARRAY_SIZE(bdw_msr_id));
+	return msr_build_context(bdw_msr_id, ARRAY_SIZE(bdw_msr_id));
 }
 
 static struct dmi_system_id msr_save_dmi_table[] = {
@@ -405,9 +416,58 @@ static struct dmi_system_id msr_save_dmi_table[] = {
 	{}
 };
 
+static int msr_save_cpuid_features(const struct x86_cpu_id *c)
+{
+	u32 cpuid_msr_id[] = {
+		MSR_AMD64_CPUID_FN_1,
+	};
+
+	pr_info("x86/pm: family %#hx cpu detected, MSR saving is needed during suspending.\n",
+		c->family);
+
+	return msr_build_context(cpuid_msr_id, ARRAY_SIZE(cpuid_msr_id));
+}
+
+static const struct x86_cpu_id msr_save_cpu_table[] = {
+	{
+		.vendor = X86_VENDOR_AMD,
+		.family = 0x15,
+		.model = X86_MODEL_ANY,
+		.feature = X86_FEATURE_ANY,
+		.driver_data = (kernel_ulong_t)msr_save_cpuid_features,
+	},
+	{
+		.vendor = X86_VENDOR_AMD,
+		.family = 0x16,
+		.model = X86_MODEL_ANY,
+		.feature = X86_FEATURE_ANY,
+		.driver_data = (kernel_ulong_t)msr_save_cpuid_features,
+	},
+	{}
+};
+
+typedef int (*pm_cpu_match_t)(const struct x86_cpu_id *);
+static int pm_cpu_check(const struct x86_cpu_id *c)
+{
+	const struct x86_cpu_id *m;
+	int ret = 0;
+
+	m = x86_match_cpu(msr_save_cpu_table);
+	if (m) {
+		pm_cpu_match_t fn;
+
+		fn = (pm_cpu_match_t)m->driver_data;
+		ret = fn(m);
+	}
+
+	return ret;
+}
+
 static int pm_check_save_msr(void)
 {
 	dmi_check_system(msr_save_dmi_table);
+	pm_cpu_check(msr_save_cpu_table);
+
 	return 0;
 }