[PATCH 1/2] KVM: arm64: Move pmu hyp code under hyp's Makefile to avoid instrumentation

James Morse
2019-05-21T17:25:53Z

KVM's pmu.c contains the __hyp_text needed to switch the pmu registers
between host and guest. Because this isn't covered by the 'hyp' Makefile,
it can be built with kasan and friends when these are enabled in Kconfig.

When starting a guest, this results in:
| Kernel panic - not syncing: HYP panic:
| PS:a00003c9 PC:000083000028ada0 ESR:86000007
| FAR:000083000028ada0 HPFAR:0000000029df5300 PAR:0000000000000000
| VCPU:000000004e10b7d6
| CPU: 0 PID: 3088 Comm: qemu-system-aar Not tainted 5.2.0-rc1 #11026
| Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Plat
| Call trace:
| dump_backtrace+0x0/0x200
| show_stack+0x20/0x30
| dump_stack+0xec/0x158
| panic+0x1ec/0x420
| panic+0x0/0x420
| SMP: stopping secondary CPUs
| Kernel Offset: disabled
| CPU features: 0x002,25006082
| Memory Limit: none
| ---[ end Kernel panic - not syncing: HYP panic:

This is caused by functions in pmu.c calling the instrumented
code, which isn't mapped to hyp. From objdump -r:
| RELOCATION RECORDS FOR [.hyp.text]:
| OFFSET TYPE VALUE
| 0000000000000010 R_AARCH64_CALL26 __sanitizer_cov_trace_pc
| 0000000000000018 R_AARCH64_CALL26 __asan_load4_noabort
| 0000000000000024 R_AARCH64_CALL26 __asan_load4_noabort

Move the affected code to a new file under 'hyp's Makefile.

Fixes: 3d91befbb3a0 ("arm64: KVM: Enable !VHE support for :G/:H perf event modifiers")
Cc: Andrew Murray <Andrew.Murray@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
---
arch/arm64/kvm/hyp/switch.c | 39 +++++++++++++++++++++++++++++++++++++
arch/arm64/kvm/pmu.c | 38 ------------------------------------
2 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 22b4c335e0b2..030c3fa28e0e 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -16,6 +16,7 @@
*/

#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
#include <linux/types.h>
#include <linux/jump_label.h>
#include <uapi/linux/psci.h>
@@ -703,3 +704,41 @@ void __hyp_text __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)

unreachable();
}
+
+/**
+ * Disable host events, enable guest events
+ */
+bool __hyp_text __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
+{
+ struct kvm_host_data *host;
+ struct kvm_pmu_events *pmu;
+
+ host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
+ pmu = &host->pmu_events;
+
+ if (pmu->events_host)
+ write_sysreg(pmu->events_host, pmcntenclr_el0);
+
+ if (pmu->events_guest)
+ write_sysreg(pmu->events_guest, pmcntenset_el0);
+
+ return (pmu->events_host || pmu->events_guest);
+}
+
+/**
+ * Disable guest events, enable host events
+ */
+void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
+{
+ struct kvm_host_data *host;
+ struct kvm_pmu_events *pmu;
+
+ host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
+ pmu = &host->pmu_events;
+
+ if (pmu->events_guest)
+ write_sysreg(pmu->events_guest, pmcntenclr_el0);
+
+ if (pmu->events_host)
+ write_sysreg(pmu->events_host, pmcntenset_el0);
+}
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index 3da94a5bb6b7..e71d00bb5271 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -53,44 +53,6 @@ void kvm_clr_pmu_events(u32 clr)
ctx->pmu_events.events_guest &= ~clr;
}

-/**
- * Disable host events, enable guest events
- */
-bool __hyp_text __pmu_switch_to_guest(struct kvm_cpu_context *host_ctxt)
-{
- struct kvm_host_data *host;
- struct kvm_pmu_events *pmu;
-
- host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
- pmu = &host->pmu_events;
-
- if (pmu->events_host)
- write_sysreg(pmu->events_host, pmcntenclr_el0);
-
- if (pmu->events_guest)
- write_sysreg(pmu->events_guest, pmcntenset_el0);
-
- return (pmu->events_host || pmu->events_guest);
-}
-
-/**
- * Disable guest events, enable host events
- */
-void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
-{
- struct kvm_host_data *host;
- struct kvm_pmu_events *pmu;
-
- host = container_of(host_ctxt, struct kvm_host_data, host_ctxt);
- pmu = &host->pmu_events;
-
- if (pmu->events_guest)
- write_sysreg(pmu->events_guest, pmcntenclr_el0);
-
- if (pmu->events_host)
- write_sysreg(pmu->events_host, pmcntenset_el0);
-}
-
#define PMEVTYPER_READ_CASE(idx) \
case idx: \
return read_sysreg(pmevtyper##idx##_el0)