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Fri, 07 Aug 2026 09:43:53 -0700 (PDT) Date: Fri, 7 Aug 2026 16:43:20 +0000 In-Reply-To: <20260807164322.2970811-2-sebastianene@google.com> Mime-Version: 1.0 References: <20260807164322.2970811-2-sebastianene@google.com> X-Mailer: git-send-email 2.55.0.654.g21b8a5bc05-goog Message-ID: <20260807164322.2970811-12-sebastianene@google.com> Subject: [PATCH v2 10/13] KVM: arm64: Restrict host updates to GITS_CTLR From: Sebastian Ene To: catalin.marinas@arm.com, fuad.tabba@linux.dev, joey.gouly@arm.com, mark.rutland@arm.com, maz@kernel.org, oupton@kernel.org, rananta@google.com, Sascha.Bischoff@arm.com, suzuki.poulose@arm.com, will@kernel.org Cc: kvmarm@lists.linux.dev, android-kvm@google.com, bgrzesik@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, nathan@kernel.org, perlarsen@google.com, sebastianene@google.com, seiden@linux.ibm.com, smostafa@google.com, tglx@kernel.org, vdonnefort@google.com, vladimir.murzin@arm.com, yuzenghui@huawei.com, zenghui.yu@linux.dev Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260807_094355_690813_0F0366ED X-CRM114-Status: GOOD ( 12.23 ) 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 unpredictable hardware behavior when the host tries to enable the ITS while it is not in quiescent state. Signed-off-by: Sebastian Ene --- arch/arm64/kvm/hyp/nvhe/its_emulate.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/its_emulate.c b/arch/arm64/kvm/hyp/nvhe/its_emulate.c index 5629e2a070df..b9b71aa18d48 100644 --- a/arch/arm64/kvm/hyp/nvhe/its_emulate.c +++ b/arch/arm64/kvm/hyp/nvhe/its_emulate.c @@ -403,8 +403,35 @@ static void cwriter_read(struct pkvm_protected_reg *region, u64 offset, u64 *rea *read = readq_relaxed(its->base + GITS_CWRITER); } +static void ctlr_read(struct pkvm_protected_reg *region, u64 offset, u64 *read) +{ + struct its_priv_state *its = region->priv; + *read = readl_relaxed(its->base + GITS_CTLR); +} + +static void ctlr_write(struct pkvm_protected_reg *region, u64 offset, u64 value) +{ + struct its_priv_state *its = region->priv; + bool is_quiescent, is_enabled; + u32 ctlr; + + ctlr = readl_relaxed(its->base + GITS_CTLR); + is_quiescent = !!(ctlr & GITS_CTLR_QUIESCENT); + is_enabled = !!(ctlr & GITS_CTLR_ENABLE); + + /* + * If it's disabled and not in quiescent state and it tries to enable + * it, bail out. + */ + if (!is_enabled && (value & GITS_CTLR_ENABLE) && !is_quiescent) + return; + + writel_relaxed(value, its->base + GITS_CTLR); +} + static struct its_handler its_handlers[] = { ITS_HANDLER(GITS_CWRITER, sizeof(u64), cwriter_write, cwriter_read), + ITS_HANDLER(GITS_CTLR, sizeof(u32), ctlr_write, ctlr_read), {}, }; -- 2.55.0.654.g21b8a5bc05-goog