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Thu, 01 Oct 2026 07:29:16 -0700 (PDT) Date: Thu, 1 Oct 2026 15:28:47 +0100 In-Reply-To: <20261001142849.3367614-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20261001142849.3367614-1-vdonnefort@google.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog Message-ID: <20261001142849.3367614-17-vdonnefort@google.com> Subject: [PATCH v6 16/18] KVM: arm64: Reject hyp trace descriptors with fewer CPUs than hyp_nr_cpus From: Vincent Donnefort To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261001_152919_496220_A9B83316 X-CRM114-Status: GOOD ( 12.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org While a trace descriptor with fewer CPUs than hyp_nr_cpus currently causes no functional issue, such a configuration is invalid and would cause the hypervisor to skip ring buffer initialization when allocating backing pages in EL2. Enforce nr_cpus == hyp_nr_cpus during trace descriptor validation to guarantee that every possible CPU has a valid ring buffer descriptor. Signed-off-by: Vincent Donnefort Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba --- arch/arm64/kvm/hyp/nvhe/trace.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trace.c index 47680a949f61..e9e584694506 100644 --- a/arch/arm64/kvm/hyp/nvhe/trace.c +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -181,6 +181,9 @@ static bool hyp_trace_desc_is_valid(struct hyp_trace_desc *desc, size_t desc_siz desc_end = (void *)desc + desc_size; nr_bpages = desc->bpages_backing_size / sizeof(struct simple_buffer_page); + if (desc->trace_buffer_desc.nr_cpus != hyp_nr_cpus) + return false; + for_each_ring_buffer_desc(rb_desc, cpu, &desc->trace_buffer_desc) { /* Can we read nr_page_va? */ if ((void *)rb_desc + struct_size(rb_desc, page_va, 0) > desc_end) -- 2.56.0.rc1.315.gc6ed9934b7-goog