The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2a3f93459d689d990b3ecfbe782fec89b97d3279 Mon Sep 17 00:00:00 2001

From: Marc Zyngier marc.zyngier@arm.com Date: Thu, 27 Sep 2018 16:53:22 +0100 Subject: [PATCH] arm64: KVM: Sanitize PSTATE.M when being set from userspace

Not all execution modes are valid for a guest, and some of them depend on what the HW actually supports. Let's verify that what userspace provides is compatible with both the VM settings and the HW capabilities.

Cc: stable@vger.kernel.org Fixes: 0d854a60b1d7 ("arm64: KVM: enable initialization of a 32bit vcpu") Reviewed-by: Christoffer Dall christoffer.dall@arm.com Reviewed-by: Mark Rutland mark.rutland@arm.com Reviewed-by: Dave Martin Dave.Martin@arm.com Signed-off-by: Marc Zyngier marc.zyngier@arm.com Signed-off-by: Will Deacon will.deacon@arm.com

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 3088463bafc1..a6c9fbaeaefc 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -152,17 +152,25 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) }

if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) { - u32 mode = (*(u32 *)valp) & PSR_AA32_MODE_MASK; + u64 mode = (*(u64 *)valp) & PSR_AA32_MODE_MASK; switch (mode) { case PSR_AA32_MODE_USR: + if (!system_supports_32bit_el0()) + return -EINVAL; + break; case PSR_AA32_MODE_FIQ: case PSR_AA32_MODE_IRQ: case PSR_AA32_MODE_SVC: case PSR_AA32_MODE_ABT: case PSR_AA32_MODE_UND: + if (!vcpu_el1_is_32bit(vcpu)) + return -EINVAL; + break; case PSR_MODE_EL0t: case PSR_MODE_EL1t: case PSR_MODE_EL1h: + if (vcpu_el1_is_32bit(vcpu)) + return -EINVAL; break; default: err = -EINVAL;