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Tue, 10 Mar 2026 05:49:55 -0700 (PDT) Date: Tue, 10 Mar 2026 12:49:30 +0000 In-Reply-To: <20260310124933.830025-1-sebastianene@google.com> Mime-Version: 1.0 References: <20260310124933.830025-1-sebastianene@google.com> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog Message-ID: <20260310124933.830025-12-sebastianene@google.com> Subject: [PATCH 11/14] KVM: arm64: Restrict host updates to GITS_CTLR From: Sebastian Ene To: alexandru.elisei@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, android-kvm@google.com Cc: catalin.marinas@arm.com, dbrazdil@google.com, joey.gouly@arm.com, kees@kernel.org, mark.rutland@arm.com, maz@kernel.org, oupton@kernel.org, perlarsen@google.com, qperret@google.com, rananta@google.com, sebastianene@google.com, smostafa@google.com, suzuki.poulose@arm.com, tabba@google.com, tglx@kernel.org, vdonnefort@google.com, bgrzesik@google.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-20260310_054958_080429_025FBFF3 X-CRM114-Status: GOOD ( 10.62 ) 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 | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/its_emulate.c b/arch/arm64/kvm/hyp/nvhe/its_emulate.c index 4782a9a24caa..539d2ee3b58e 100644 --- a/arch/arm64/kvm/hyp/nvhe/its_emulate.c +++ b/arch/arm64/kvm/hyp/nvhe/its_emulate.c @@ -274,6 +274,23 @@ static void cwriter_read(struct its_priv_state *its, u64 offset, u64 *read) *read = readq_relaxed(its->base + GITS_CWRITER); } +static void ctlr_read(struct its_priv_state *its, u64 offset, u64 *read) +{ + *read = readq_relaxed(its->base + GITS_CTLR); +} + +static void ctlr_write(struct its_priv_state *its, u64 offset, u64 value) +{ + u64 ctlr = readq_relaxed(its->base + GITS_CTLR); + bool is_quiescent = !!(ctlr & GITS_CTLR_QUIESCENT); + bool is_enabled = !!(ctlr & GITS_CTLR_ENABLE); + + if (!is_enabled && (value & GITS_CTLR_ENABLE) && !is_quiescent) + return; + + writeq_relaxed(value, its->base + GITS_CTLR); +} + #define ITS_HANDLER(off, sz, write_cb, read_cb) \ { \ .offset = (off), \ @@ -284,6 +301,7 @@ static void cwriter_read(struct its_priv_state *its, u64 offset, u64 *read) static struct its_handler its_handlers[] = { ITS_HANDLER(GITS_CWRITER, sizeof(u64), cwriter_write, cwriter_read), + ITS_HANDLER(GITS_CTLR, sizeof(u64), ctlr_write, ctlr_read), {}, }; -- 2.53.0.473.g4a7958ca14-goog