linux-kernel - Re: [PATCH v2 093/144] KVM: selftests: Track kvm_vcpu object in tsc_scaling

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Message-ID: <20220608161350.abq5hqr6t3wu5q52@gator>
Date:   Wed, 8 Jun 2022 18:13:50 +0200
From:   Andrew Jones <drjones@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Matlack <dmatlack@...gle.com>,
        Ben Gardon <bgardon@...gle.com>,
        Oliver Upton <oupton@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 093/144] KVM: selftests: Track kvm_vcpu object in
 tsc_scaling_sync

On Fri, Jun 03, 2022 at 12:42:40AM +0000, Sean Christopherson wrote:
> Track the added 'struct kvm_vcpu' object in tsc_scaling_sync instead of
> relying purely on the VM + vcpu_id combination.  Ideally, the test
> wouldn't need to manually manage vCPUs, but the need to invoke a per-VM
> ioctl before creating vCPUs is not handled by the selftests framework,
> at least not yet...
> 
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  .../selftests/kvm/x86_64/tsc_scaling_sync.c     | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
> index f0083d8cfe98..b7cd5c47fc53 100644
> --- a/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
> +++ b/tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c
> @@ -46,38 +46,41 @@ static void guest_code(void)
>  
>  static void *run_vcpu(void *_cpu_nr)
>  {
> -	unsigned long cpu = (unsigned long)_cpu_nr;
> +	unsigned long vcpu_id = (unsigned long)_cpu_nr;
>  	unsigned long failures = 0;
>  	static bool first_cpu_done;
> +	struct kvm_vcpu *vcpu;
>  
>  	/* The kernel is fine, but vm_vcpu_add_default() needs locking */
>  	pthread_spin_lock(&create_lock);
>  
> -	vm_vcpu_add_default(vm, cpu, guest_code);
> +	vm_vcpu_add_default(vm, vcpu_id, guest_code);
> +	vcpu = vcpu_get(vm, vcpu_id);
>  
>  	if (!first_cpu_done) {
>  		first_cpu_done = true;
> -		vcpu_set_msr(vm, cpu, MSR_IA32_TSC, TEST_TSC_OFFSET);
> +		vcpu_set_msr(vm, vcpu->id, MSR_IA32_TSC, TEST_TSC_OFFSET);
>  	}
>  
>  	pthread_spin_unlock(&create_lock);
>  
>  	for (;;) {
> -		volatile struct kvm_run *run = vcpu_state(vm, cpu);
> +		volatile struct kvm_run *run = vcpu->run;
>                  struct ucall uc;
>  
> -                vcpu_run(vm, cpu);
> +		vcpu_run(vm, vcpu->id);
>                  TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
>                              "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
>                              run->exit_reason,
>                              exit_reason_str(run->exit_reason));
>  
> -                switch (get_ucall(vm, cpu, &uc)) {
> +		switch (get_ucall(vm, vcpu->id, &uc)) {

The two changes above show that this file had some space vs. tab issues.
I just checked and these two lines weren't the only ones, so I guess we
can add cleaning up whitespace of x86_64/tsc_scaling_sync.c to the rainy
day TODO.

Thanks,
drew

>                  case UCALL_DONE:
>  			goto out;
>  
>                  case UCALL_SYNC:
> -			printf("Guest %ld sync %lx %lx %ld\n", cpu, uc.args[2], uc.args[3], uc.args[2] - uc.args[3]);
> +			printf("Guest %d sync %lx %lx %ld\n", vcpu->id,
> +			       uc.args[2], uc.args[3], uc.args[2] - uc.args[3]);
>  			failures++;
>  			break;
>  
> -- 
> 2.36.1.255.ge46751e96f-goog
>