@@ -86,11 +86,13 @@ static inline void vcpu_set_thumb(struct kvm_vcpu *vcpu)
*vcpu_cpsr(vcpu) |= COMPAT_PSR_T_BIT;
}
+/*
+ * vcpu_reg should always be passed a register number coming from a
+ * read of ESR_EL2. Otherwise, it may give the wrong result on AArch32
+ * with banked registers.
+ */
static inline unsigned long *vcpu_reg(const struct kvm_vcpu *vcpu, u8 reg_num)
{
- if (vcpu_mode_is_32bit(vcpu))
- return vcpu_reg32(vcpu, reg_num);
-
return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.regs[reg_num];
}
@@ -48,7 +48,7 @@ static void prepare_fault32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset)
/* Note: These now point to the banked copies */
*vcpu_spsr(vcpu) = new_spsr_value;
- *vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
+ *vcpu_reg32(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
/* Branch to exception vector */
if (sctlr & (1 << 13))
This is a note to let you know that I have just added a patch titled arm64: KVM: Fix AArch32 to AArch64 register mapping to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt22. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 580580d9cbb5d7e8c9965defdbdfbebf4cca038c Mon Sep 17 00:00:00 2001 From: Marc Zyngier <marc.zyngier@arm.com> Date: Mon, 16 Nov 2015 10:28:17 +0000 Subject: arm64: KVM: Fix AArch32 to AArch64 register mapping commit c0f0963464c24e034b858441205455bf2a5d93ad upstream. When running a 32bit guest under a 64bit hypervisor, the ARMv8 architecture defines a mapping of the 32bit registers in the 64bit space. This includes banked registers that are being demultiplexed over the 64bit ones. On exceptions caused by an operation involving a 32bit register, the HW exposes the register number in the ESR_EL2 register. It was so far understood that SW had to distinguish between AArch32 and AArch64 accesses (based on the current AArch32 mode and register number). It turns out that I misinterpreted the ARM ARM, and the clue is in D1.20.1: "For some exceptions, the exception syndrome given in the ESR_ELx identifies one or more register numbers from the issued instruction that generated the exception. Where the exception is taken from an Exception level using AArch32 these register numbers give the AArch64 view of the register." Which means that the HW is already giving us the translated version, and that we shouldn't try to interpret it at all (for example, doing an MMIO operation from the IRQ mode using the LR register leads to very unexpected behaviours). The fix is thus not to perform a call to vcpu_reg32() at all from vcpu_reg(), and use whatever register number is supplied directly. The only case we need to find out about the mapping is when we actively generate a register access, which only occurs when injecting a fault in a guest. Reviewed-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/arm64/include/asm/kvm_emulate.h | 8 +++++--- arch/arm64/kvm/inject_fault.c | 2 +- 2 files changed, 6 insertions(+), 4 deletions(-)