The SCV facility will be disabled at runtime in the host by PR KVM by
the next change, emulate it in the facility unavailable handler.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/traps.c | 45 +++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 11741703d26e..6e4eaa6bf58d 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -58,6 +58,7 @@
#include <asm/ppc-opcode.h>
#include <asm/rio.h>
#include <asm/fadump.h>
+#include <asm/sstep.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/debug.h>
@@ -1778,6 +1779,49 @@ DEFINE_INTERRUPT_HANDLER(facility_unavailable_exception)
return;
}
+ if (status == FSCR_SCV_LG) {
+ u32 lev;
+ ppc_inst_t instr;
+
+ /* If we didn't advertise the feature to userspace, SIGILL */
+ if (!(cur_cpu_spec->cpu_user_features2 & PPC_FEATURE2_SCV))
+ goto out_msg;
+
+ /*
+ * PR KVM disables the FSCR[SCV] facility even if the rest of
+ * the kernel and userspace thought SCV was enabled. THis
+ * causes scv instructions executed by both the host and the
+ * guest to come here, in their respective kernels.
+ *
+ * If radix is enabled then PR KVM can not be in use and can
+ * not be our hypervisor, so treat this as a normal illegal
+ * instruction. If we are hash guest or host, we might need
+ * to emulate a legitimate scv interrupt here.
+ */
+ if (radix_enabled())
+ goto out_msg;
+
+ /*
+ * User is making SCV call with SCV disabled. Emulate it.
+ */
+ if (get_user_instr(instr, (void __user *)regs->nip)) {
+ pr_err("Failed to fetch the user instruction\n");
+ return;
+ }
+
+ instword = ppc_inst_val(instr);
+ if (WARN_ON_ONCE((instword & 0xfffff01f) != 0x44000001))
+ goto out;
+
+ lev = (instword >> 5) & 0x7f;
+ if (lev == 0) {
+ if (emulate_step(regs, instr) > 0)
+ return;
+ else
+ pr_err_ratelimited("Failed to emulate SCV\n");
+ }
+ }
+
if (status == FSCR_TM_LG) {
/*
* If we're here then the hardware is TM aware because it
@@ -1799,6 +1843,7 @@ DEFINE_INTERRUPT_HANDLER(facility_unavailable_exception)
return;
}
+out_msg:
pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at
0x%lx, MSR=%lx\n",
hv ? "Hypervisor " : "", facility, status, regs->nip,
regs->msr);
--
2.23.0
