[PATCH 5.0 174/238] arm64: KVM: Fix architecturally invalid reset value for FPEXC32_EL2

From: Greg Kroah-Hartman
Date: Fri Mar 22 2019 - 08:28:30 EST

5.0-stable review patch. If anyone has any objections, please let me know.


From: Dave Martin <Dave.Martin@xxxxxxx>

commit c88b093693ccbe41991ef2e9b1d251945e6e54ed upstream.

Due to what looks like a typo dating back to the original addition
of FPEXC32_EL2 handling, KVM currently initialises this register to
an architecturally invalid value.

As a result, the VECITR field (RES1) in bits [10:8] is initialised
with 0, and the two reserved (RES0) bits [6:5] are initialised with
1. (In the Common VFP Subarchitecture as specified by ARMv7-A,
these two bits were IMP DEF. ARMv8-A removes them.)

This patch changes the reset value from 0x70 to 0x700, which
reflects the architectural constraints and is presumably what was
originally intended.

Cc: <stable@xxxxxxxxxxxxxxx> # 4.12.x-
Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
Fixes: 62a89c44954f ("arm64: KVM: 32bit handling of coprocessor traps")
Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/arm64/kvm/sys_regs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1476,7 +1476,7 @@ static const struct sys_reg_desc sys_reg

{ SYS_DESC(SYS_DACR32_EL2), NULL, reset_unknown, DACR32_EL2 },
{ SYS_DESC(SYS_IFSR32_EL2), NULL, reset_unknown, IFSR32_EL2 },
- { SYS_DESC(SYS_FPEXC32_EL2), NULL, reset_val, FPEXC32_EL2, 0x70 },
+ { SYS_DESC(SYS_FPEXC32_EL2), NULL, reset_val, FPEXC32_EL2, 0x700 },

static bool trap_dbgidr(struct kvm_vcpu *vcpu,