Patch "KVM: selftests: Avoid infinite loop in hyperv_features when invtsc is missing" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    KVM: selftests: Avoid infinite loop in hyperv_features when invtsc is missing

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     kvm-selftests-avoid-infinite-loop-in-hyperv_features.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit faf78843f99b0bb36eeb414dc8f4afacd880babd
Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Date:   Mon Jan 29 09:58:46 2024 +0100

    KVM: selftests: Avoid infinite loop in hyperv_features when invtsc is missing
    
    [ Upstream commit 8ad4855273488c9bd5320b3fee80f66f0023f326 ]
    
    When X86_FEATURE_INVTSC is missing, guest_test_msrs_access() was supposed
    to skip testing dependent Hyper-V invariant TSC feature. Unfortunately,
    'continue' does not lead to that as stage is not incremented. Moreover,
    'vm' allocated with vm_create_with_one_vcpu() is not freed and the test
    runs out of available file descriptors very quickly.
    
    Fixes: bd827bd77537 ("KVM: selftests: Test Hyper-V invariant TSC control")
    Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240129085847.2674082-1-vkuznets@xxxxxxxxxx
    Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_features.c b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
index 9f28aa276c4e..a726831b8024 100644
--- a/tools/testing/selftests/kvm/x86_64/hyperv_features.c
+++ b/tools/testing/selftests/kvm/x86_64/hyperv_features.c
@@ -454,7 +454,7 @@ static void guest_test_msrs_access(void)
 		case 44:
 			/* MSR is not available when CPUID feature bit is unset */
 			if (!has_invtsc)
-				continue;
+				goto next_stage;
 			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
 			msr->write = false;
 			msr->fault_expected = true;
@@ -462,7 +462,7 @@ static void guest_test_msrs_access(void)
 		case 45:
 			/* MSR is vailable when CPUID feature bit is set */
 			if (!has_invtsc)
-				continue;
+				goto next_stage;
 			vcpu_set_cpuid_feature(vcpu, HV_ACCESS_TSC_INVARIANT);
 			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
 			msr->write = false;
@@ -471,7 +471,7 @@ static void guest_test_msrs_access(void)
 		case 46:
 			/* Writing bits other than 0 is forbidden */
 			if (!has_invtsc)
-				continue;
+				goto next_stage;
 			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
 			msr->write = true;
 			msr->write_val = 0xdeadbeef;
@@ -480,7 +480,7 @@ static void guest_test_msrs_access(void)
 		case 47:
 			/* Setting bit 0 enables the feature */
 			if (!has_invtsc)
-				continue;
+				goto next_stage;
 			msr->idx = HV_X64_MSR_TSC_INVARIANT_CONTROL;
 			msr->write = true;
 			msr->write_val = 1;
@@ -513,6 +513,7 @@ static void guest_test_msrs_access(void)
 			return;
 		}
 
+next_stage:
 		stage++;
 		kvm_vm_free(vm);
 	}