[PATCH v2 10/13] KVM: arm64: Restrict host updates to GITS_CTLR
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COLD33d
From: Sebastian Ene <hidden>
Date: 2026-08-07 16:43:55
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
Revision v2 of 2 in this series.
Revisions (2)
- rfc [diff vs current]
- v2 current
Prevent unpredictable hardware behavior when the host tries to enable the ITS while it is not in quiescent state. Signed-off-by: Sebastian Ene <redacted> --- 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