lkml.org 
[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
Subject[PATCH v5 6/8] KVM: arm64: Add hypervisor overflow stack
From
Allocate and switch to 16-byte aligned secondary stack on overflow. This
provides us stack space to better handle overflows; and is used in
a subsequent patch to dump the hypervisor stacktrace. The overflow stack
is only allocated if CONFIG_NVHE_EL2_DEBUG is enabled, as hypervisor
stacktraces is a debug feature dependent on CONFIG_NVHE_EL2_DEBUG.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---

Changes in v4:
- Update comment to clarify resetting the SP to the top of the stack
only happens if CONFIG_NVHE_EL2_DEBUG is disabled, per Fuad


arch/arm64/kvm/hyp/nvhe/host.S | 11 ++++++++---
arch/arm64/kvm/hyp/nvhe/switch.c | 5 +++++
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index be6d844279b1..a0c4b4f1549f 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -179,13 +179,18 @@ SYM_FUNC_END(__host_hvc)
b hyp_panic

.L__hyp_sp_overflow\@:
+#ifdef CONFIG_NVHE_EL2_DEBUG
+ /* Switch to the overflow stack */
+ adr_this_cpu sp, hyp_overflow_stack + PAGE_SIZE, x0
+#else
/*
- * Reset SP to the top of the stack, to allow handling the hyp_panic.
- * This corrupts the stack but is ok, since we won't be attempting
- * any unwinding here.
+ * If !CONFIG_NVHE_EL2_DEBUG, reset SP to the top of the stack, to
+ * allow handling the hyp_panic. This corrupts the stack but is ok,
+ * since we won't be attempting any unwinding here.
*/
ldr_this_cpu x0, kvm_init_params + NVHE_INIT_STACK_HYP_VA, x1
mov sp, x0
+#endif

bl hyp_panic_bad_stack
ASM_BUG()
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 703a5d3f611b..efc20273a352 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -34,6 +34,11 @@ DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data);
DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);

+#ifdef CONFIG_NVHE_EL2_DEBUG
+DEFINE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], hyp_overflow_stack)
+ __aligned(16);
+#endif
+
static void __activate_traps(struct kvm_vcpu *vcpu)
{
u64 val;
--
2.35.1.616.g0bdcbb4464-goog
\
 
 \ /
  Last update: 2022-03-07 19:54    [W:0.110 / U:0.476 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site