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Wed, 08 Apr 2026 04:41:21 -0700 (PDT) Date: Wed, 8 Apr 2026 11:41:18 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog Message-ID: <20260408114118.422604-1-sebastianene@google.com> Subject: [PATCH v2] KVM: arm64: Reject non compliant SMCCC function calls in pKVM From: Sebastian Ene To: catalin.marinas@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com Cc: joey.gouly@arm.com, korneld@google.com, maz@kernel.org, mrigendra.chaubey@gmail.com, oupton@kernel.org, perlarsen@google.com, sebastianene@google.com, suzuki.poulose@arm.com, will@kernel.org, yuzenghui@huawei.com Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260408_044124_260438_3C2D9B60 X-CRM114-Status: GOOD ( 12.32 ) 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 Prevent the propagation of a function-id that has the top bits set since this is not compliant with the SMCCC spec and can overlap with the already known function-id decoders. (eg. if we invoke an smc with 0xffffffffc4000012 it will be decoded as a PSCI reset call). Instead, make it clear that we don't support it and return an error. Signed-off-by: Sebastian Ene --- NOTE: This is based on linux-next, next-20260407 to avoid a minor conflict with a previously submitted patch (commit cf6348af645b). Changelog: v1 -> v2: * dropped the changes to the function signature that were accepting 64-bit function-ids. * applied Mark's suggestion to make it clear that we don't accept non standard SMCCC calls. * revised commit message & updated the title. Link to v1: https://lore.kernel.org/all/20260401123201.389906-1-sebastianene@google.com/ --- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 73f2e0221e70..cca4b07c8d61 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -805,6 +805,10 @@ static void handle_host_smc(struct kvm_cpu_context *host_ctxt) } func_id &= ~ARM_SMCCC_CALL_HINTS; + if (upper_32_bits(func_id)) { + cpu_reg(host_ctxt, 0) = SMCCC_RET_NOT_SUPPORTED; + goto exit_skip_instr; + } handled = kvm_host_psci_handler(host_ctxt, func_id); if (!handled) -- 2.53.0.1213.gd9a14994de-goog