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AJvYcCU45381U8H3LVc+nI3tInBMOTqMsr/wY1e1kJi9fOtkTODpLmhTFtbKDTMrKLy72S5PI79s8Nqw7coC8qiPsot+GgjO X-Gm-Message-State: AOJu0YxlrbjpmKc3zSVhrTEHzWRZWX8LZROOh29bDTBUHdXuRQLsiyUS AimutUoplD0v9cdOl4tYtKE8C5PX8LfDme+E3qhMgzzf+kSG5MBX+ZVQIpiM5gYI754nvvpmpcq bsw== X-Google-Smtp-Source: AGHT+IEvNqUaUJBlWS7SOO+5ifizSYXMErTQDuWBmebOu7ltgX/lzZWc9zAGvheP8PZ+HeITHDqWN/fjXZk= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a81:a108:0:b0:609:50fb:c2cf with SMTP id y8-20020a81a108000000b0060950fbc2cfmr2653020ywg.1.1710260859272; Tue, 12 Mar 2024 09:27:39 -0700 (PDT) Date: Tue, 12 Mar 2024 09:27:37 -0700 In-Reply-To: <20240312-0334bd56a139b40ffec19772@orel> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240312-0334bd56a139b40ffec19772@orel> Message-ID: Subject: Re: kernel selftest max_guest_memory_test fails when using more that 256 vCPUs From: Sean Christopherson To: Andrew Jones Cc: mlevitsk@redhat.com, kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Tue, Mar 12, 2024, Andrew Jones wrote: > On Mon, Mar 11, 2024 at 05:05:18PM -0700, Sean Christopherson wrote: > > On Mon, Mar 11, 2024, mlevitsk@redhat.com wrote: > > diff --git a/tools/testing/selftests/kvm/max_guest_memory_test.c b/tools/testing/selftests/kvm/max_guest_memory_test.c > > index 6628dc4dda89..5f9950f41313 100644 > > --- a/tools/testing/selftests/kvm/max_guest_memory_test.c > > +++ b/tools/testing/selftests/kvm/max_guest_memory_test.c > > @@ -22,10 +22,12 @@ static void guest_code(uint64_t start_gpa, uint64_t end_gpa, uint64_t stride) > > { > > uint64_t gpa; > > > > - for (gpa = start_gpa; gpa < end_gpa; gpa += stride) > > - *((volatile uint64_t *)gpa) = gpa; > > + for (;;) { > > + for (gpa = start_gpa; gpa < end_gpa; gpa += stride) > > + *((volatile uint64_t *)gpa) = gpa; > > > > - GUEST_DONE(); > > + GUEST_DONE(); > > I'd change this to a GUEST_SYNC(0), since the infinite loop otherwise > contradicts the "done-ness". Eh, the guest is "done" with an iteration/run. :-) I don't have a strong preference, I'm just biased against GUEST_SYNC() in general, as tests that heavily use GUEST_SYNC() tend to be ridiculously hard to follow/debug.