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authorMarc Zyngier <marc.zyngier@arm.com>2018-05-29 13:11:17 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2018-05-31 18:00:57 +0100
commitb4f18c063a13dfb33e3a63fe1844823e19c2265e (patch)
treebc443010e3993eb477128be3d1e5eefeae9ed408 /arch/arm64/kvm
parent55e3748e8902ff641e334226bdcb432f9a5d78d3 (diff)
arm64: KVM: Handle guest's ARCH_WORKAROUND_2 requests
In order to forward the guest's ARCH_WORKAROUND_2 calls to EL3, add a small(-ish) sequence to handle it at EL2. Special care must be taken to track the state of the guest itself by updating the workaround flags. We also rely on patching to enable calls into the firmware. Note that since we need to execute branches, this always executes after the Spectre-v2 mitigation has been applied. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kvm')
-rw-r--r--arch/arm64/kvm/hyp/hyp-entry.S38
1 files changed, 37 insertions, 1 deletions
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index bffece27b5c1..05d836979032 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -106,8 +106,44 @@ el1_hvc_guest:
*/
ldr x1, [sp] // Guest's x0
eor w1, w1, #ARM_SMCCC_ARCH_WORKAROUND_1
+ cbz w1, wa_epilogue
+
+ /* ARM_SMCCC_ARCH_WORKAROUND_2 handling */
+ eor w1, w1, #(ARM_SMCCC_ARCH_WORKAROUND_1 ^ \
+ ARM_SMCCC_ARCH_WORKAROUND_2)
cbnz w1, el1_trap
- mov x0, x1
+
+#ifdef CONFIG_ARM64_SSBD
+alternative_cb arm64_enable_wa2_handling
+ b wa2_end
+alternative_cb_end
+ get_vcpu_ptr x2, x0
+ ldr x0, [x2, #VCPU_WORKAROUND_FLAGS]
+
+ // Sanitize the argument and update the guest flags
+ ldr x1, [sp, #8] // Guest's x1
+ clz w1, w1 // Murphy's device:
+ lsr w1, w1, #5 // w1 = !!w1 without using
+ eor w1, w1, #1 // the flags...
+ bfi x0, x1, #VCPU_WORKAROUND_2_FLAG_SHIFT, #1
+ str x0, [x2, #VCPU_WORKAROUND_FLAGS]
+
+ /* Check that we actually need to perform the call */
+ hyp_ldr_this_cpu x0, arm64_ssbd_callback_required, x2
+ cbz x0, wa2_end
+
+ mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
+ smc #0
+
+ /* Don't leak data from the SMC call */
+ mov x3, xzr
+wa2_end:
+ mov x2, xzr
+ mov x1, xzr
+#endif
+
+wa_epilogue:
+ mov x0, xzr
add sp, sp, #16
eret