On 2021-02-05 11:19, Will Deacon wrote:

quoted

On Fri, Feb 05, 2021 at 09:11:00AM +0000, Steven Price wrote:

quoted

On 02/02/2021 14:11, Marc Zyngier wrote:

quoted

+	for (i = 0; i < 32; ++i) {
+		if (res.a0 & (i))
+			set_bit(i + (32 * 0), __kvm_arm_hyp_services);
+		if (res.a1 & (i))
+			set_bit(i + (32 * 1), __kvm_arm_hyp_services);
+		if (res.a2 & (i))
+			set_bit(i + (32 * 2), __kvm_arm_hyp_services);
+		if (res.a3 & (i))
+			set_bit(i + (32 * 3), __kvm_arm_hyp_services);

The bit shifts are missing, the tests should be of the form:

	if (res.a0 & (1 << i))

Or indeed using a BIT() macro.

Maybe even test_bit()?

Actually, maybe not doing things a-bit-at-a-time is less error prone.
See below what I intend to fold in.

Thanks,

        M.

diff --git a/drivers/firmware/smccc/kvm_guest.c

b/drivers/firmware/smccc/kvm_guest.c
index 00bf3c7969fc..08836f2f39ee 100644

--- a/drivers/firmware/smccc/kvm_guest.c
+++ b/drivers/firmware/smccc/kvm_guest.c

@@ -2,8 +2,8 @@

 #define pr_fmt(fmt) "smccc: KVM: " fmt

-#include <linux/init.h>
 #include <linux/arm-smccc.h>
+#include <linux/bitmap.h>
 #include <linux/kernel.h>
 #include <linux/string.h>

@@ -13,8 +13,8 @@ static DECLARE_BITMAP(__kvm_arm_hyp_services,

ARM_SMCCC_KVM_NUM_FUNCS) __ro_afte

 void __init kvm_init_hyp_services(void)
 {
-	int i;
 	struct arm_smccc_res res;
+	u32 val[4];

 	if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_HVC)
 		return;

@@ -28,16 +28,13 @@ void __init kvm_init_hyp_services(void)

 	memset(&res, 0, sizeof(res));
 	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID, &res);
-	for (i = 0; i < 32; ++i) {
-		if (res.a0 & (i))
-			set_bit(i + (32 * 0), __kvm_arm_hyp_services);
-		if (res.a1 & (i))
-			set_bit(i + (32 * 1), __kvm_arm_hyp_services);
-		if (res.a2 & (i))
-			set_bit(i + (32 * 2), __kvm_arm_hyp_services);
-		if (res.a3 & (i))
-			set_bit(i + (32 * 3), __kvm_arm_hyp_services);
-	}
+
+	val[0] = lower_32_bits(res.a0);
+	val[1] = lower_32_bits(res.a1);
+	val[2] = lower_32_bits(res.a2);
+	val[3] = lower_32_bits(res.a3);
+
+	bitmap_from_arr32(__kvm_arm_hyp_services, val, ARM_SMCCC_KVM_NUM_FUNCS);