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[184.145.4.219]) by smtp.gmail.com with ESMTPSA id b17sm3192261qka.94.2021.05.20.14.47.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 14:47:47 -0700 (PDT) Date: Thu, 20 May 2021 17:47:45 -0400 From: Peter Xu To: David Matlack Cc: kvm@vger.kernel.org, Paolo Bonzini , Andrew Jones , Ben Gardon Subject: Re: [PATCH] KVM: selftests: Fix 32-bit truncation of vm_get_max_gfn() Message-ID: References: <20210520212654.712276-1-dmatlack@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210520212654.712276-1-dmatlack@google.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, May 20, 2021 at 09:26:54PM +0000, David Matlack wrote: > vm_get_max_gfn() casts vm->max_gfn from a uint64_t to an unsigned int, > which causes the upper 32-bits of the max_gfn to get truncated. > > Nobody noticed until now likely because vm_get_max_gfn() is only used > as a mechanism to create a memslot in an unused region of the guest > physical address space (the top), and the top of the 32-bit physical > address space was always good enough. s/top/bottom/? Looks right.. thanks for fixing it! > > This fix reveals a bug in memslot_modification_stress_test which was > trying to create a dummy memslot past the end of guest physical memory. > Fix that by moving the dummy memslot lower. Would it be better to split the different fixes? > > Fixes: 52200d0d944e ("KVM: selftests: Remove duplicate guest mode handling") > Signed-off-by: David Matlack > --- > tools/testing/selftests/kvm/include/kvm_util.h | 2 +- > tools/testing/selftests/kvm/lib/kvm_util.c | 2 +- > .../testing/selftests/kvm/lib/perf_test_util.c | 2 +- > .../kvm/memslot_modification_stress_test.c | 18 +++++++++++------- > 4 files changed, 14 insertions(+), 10 deletions(-) > > diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h > index 84982eb02b29..5d9b35d09251 100644 > --- a/tools/testing/selftests/kvm/include/kvm_util.h > +++ b/tools/testing/selftests/kvm/include/kvm_util.h > @@ -303,7 +303,7 @@ bool vm_is_unrestricted_guest(struct kvm_vm *vm); > > unsigned int vm_get_page_size(struct kvm_vm *vm); > unsigned int vm_get_page_shift(struct kvm_vm *vm); > -unsigned int vm_get_max_gfn(struct kvm_vm *vm); > +uint64_t vm_get_max_gfn(struct kvm_vm *vm); > int vm_get_fd(struct kvm_vm *vm); > > unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size); > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c > index 1af1009254c4..aeffbb1e7c7d 100644 > --- a/tools/testing/selftests/kvm/lib/kvm_util.c > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c > @@ -2058,7 +2058,7 @@ unsigned int vm_get_page_shift(struct kvm_vm *vm) > return vm->page_shift; > } > > -unsigned int vm_get_max_gfn(struct kvm_vm *vm) > +uint64_t vm_get_max_gfn(struct kvm_vm *vm) > { > return vm->max_gfn; > } > diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c > index 81490b9b4e32..ed4424ed26d6 100644 > --- a/tools/testing/selftests/kvm/lib/perf_test_util.c > +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c > @@ -80,7 +80,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus, > */ > TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm), > "Requested more guest memory than address space allows.\n" > - " guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n", > + " guest pages: %lx max gfn: %lx vcpus: %d wss: %lx]\n", If to fix it, maybe start to use PRIu64 (and include inttypes.h)? Thanks, -- Peter Xu