@@ -159,13 +159,9 @@ __kvm_vcpu_return:
@ Don't trap coprocessor accesses for host kernel
set_hstr vmexit
set_hdcr vmexit
- set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11))
+ set_hcptr vmexit, (HCPTR_TTA | HCPTR_TCP(10) | HCPTR_TCP(11)), after_vfp_restore
#ifdef CONFIG_VFPv3
- @ Save floating point registers we if let guest use them.
- tst r2, #(HCPTR_TCP(10) | HCPTR_TCP(11))
- bne after_vfp_restore
-
@ Switch VFP/NEON hardware state to the host's
add r7, vcpu, #VCPU_VFP_GUEST
store_vfp_state r7
@@ -177,6 +173,8 @@ after_vfp_restore:
@ Restore FPEXC_EN which we clobbered on entry
pop {r2}
VFPFMXR FPEXC, r2
+#else
+after_vfp_restore:
#endif
@ Reset Hyp-role
@@ -467,7 +465,7 @@ switch_to_guest_vfp:
push {r3-r7}
@ NEON/VFP used. Turn on VFP access.
- set_hcptr vmexit, (HCPTR_TCP(10) | HCPTR_TCP(11))
+ set_hcptr vmtrap, (HCPTR_TCP(10) | HCPTR_TCP(11))
@ Switch VFP/NEON hardware state to the guest's
add r7, r0, #VCPU_VFP_HOST
@@ -578,8 +578,13 @@ vcpu .req r0 @ vcpu pointer always in r0
.endm
/* Configures the HCPTR (Hyp Coprocessor Trap Register) on entry/return
- * (hardware reset value is 0). Keep previous value in r2. */
-.macro set_hcptr operation, mask
+ * (hardware reset value is 0). Keep previous value in r2.
+ * An ISB is emited on vmexit/vmtrap, but executed on vmexit only if
+ * VFP wasn't already enabled (always executed on vmtrap).
+ * If a label is specified with vmexit, it is branched to if VFP wasn't
+ * enabled.
+ */
+.macro set_hcptr operation, mask, label = none
mrc p15, 4, r2, c1, c1, 2
ldr r3, =\mask
.if \operation == vmentry
@@ -588,6 +593,17 @@ vcpu .req r0 @ vcpu pointer always in r0
bic r3, r2, r3 @ Don't trap defined coproc-accesses
.endif
mcr p15, 4, r3, c1, c1, 2
+ .if \operation != vmentry
+ .if \operation == vmexit
+ tst r2, #(HCPTR_TCP(10) | HCPTR_TCP(11))
+ beq 1f
+ .endif
+ isb
+ .if \label != none
+ b \label
+ .endif
+1:
+ .endif
.endm
/* Configures the HDCR (Hyp Debug Configuration Register) on entry/return
This is a note to let you know that I have just added a patch titled arm: KVM: force execution of HCPTR access on VM exit 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-ckt15. 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 45420160e841a0c92c866edd15d9ce6b79b55313 Mon Sep 17 00:00:00 2001 From: Marc Zyngier <marc.zyngier@arm.com> Date: Mon, 16 Mar 2015 10:59:43 +0000 Subject: arm: KVM: force execution of HCPTR access on VM exit commit 85e84ba31039595995dae80b277378213602891b upstream. On VM entry, we disable access to the VFP registers in order to perform a lazy save/restore of these registers. On VM exit, we restore access, test if we did enable them before, and save/restore the guest/host registers if necessary. In this sequence, the FPEXC register is always accessed, irrespective of the trapping configuration. If the guest didn't touch the VFP registers, then the HCPTR access has now enabled such access, but we're missing a barrier to ensure architectural execution of the new HCPTR configuration. If the HCPTR access has been delayed/reordered, the subsequent access to FPEXC will cause a trap, which we aren't prepared to handle at all. The same condition exists when trapping to enable VFP for the guest. The fix is to introduce a barrier after enabling VFP access. In the vmexit case, it can be relaxed to only takes place if the guest hasn't accessed its view of the VFP registers, making the access to FPEXC safe. The set_hcptr macro is modified to deal with both vmenter/vmexit and vmtrap operations, and now takes an optional label that is branched to when the guest hasn't touched the VFP registers. Reported-by: Vikram Sethi <vikrams@codeaurora.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/arm/kvm/interrupts.S | 10 ++++------ arch/arm/kvm/interrupts_head.S | 20 ++++++++++++++++++-- 2 files changed, 22 insertions(+), 8 deletions(-)