@@ -16,7 +16,9 @@
extern s32 patch__call_flush_count_cache;
extern s32 patch__flush_count_cache_return;
extern s32 patch__flush_link_stack_return;
+extern s32 patch__call_kvm_flush_link_stack;
extern long flush_count_cache;
+extern long kvm_flush_link_stack;
#endif /* _ASM_POWERPC_ASM_PROTOTYPES_H */
@@ -391,6 +391,9 @@ static void toggle_count_cache_flush(bool enable)
if (!enable) {
patch_instruction_site(&patch__call_flush_count_cache, PPC_INST_NOP);
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+ patch_instruction_site(&patch__call_kvm_flush_link_stack, PPC_INST_NOP);
+#endif
pr_info("link-stack-flush: software flush disabled.\n");
link_stack_flush_enabled = false;
no_count_cache_flush();
@@ -401,6 +404,12 @@ static void toggle_count_cache_flush(bool enable)
patch_branch_site(&patch__call_flush_count_cache,
(u64)&flush_count_cache, BRANCH_SET_LINK);
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+ // This enables the branch from guest_exit_cont to kvm_flush_link_stack
+ patch_branch_site(&patch__call_kvm_flush_link_stack,
+ (u64)&kvm_flush_link_stack, BRANCH_SET_LINK);
+#endif
+
pr_info("link-stack-flush: software flush enabled.\n");
link_stack_flush_enabled = true;
@@ -18,6 +18,7 @@
*/
#include <asm/ppc_asm.h>
+#include <asm/code-patching-asm.h>
#include <asm/kvm_asm.h>
#include <asm/reg.h>
#include <asm/mmu.h>
@@ -1193,6 +1194,10 @@ mc_cont:
bl kvmhv_accumulate_time
#endif
+ /* Possibly flush the link stack here. */
+1: nop
+ patch_site 1b patch__call_kvm_flush_link_stack
+
mr r3, r12
/* Increment exit count, poke other threads to exit */
bl kvmhv_commence_exit
@@ -1611,6 +1616,21 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mtlr r0
blr
+.balign 32
+.global kvm_flush_link_stack
+kvm_flush_link_stack:
+ /* Save LR into r0 */
+ mflr r0
+
+ /* Flush the link stack. On Power8 it's up to 32 entries in size. */
+ .rept 32
+ bl .+4
+ .endr
+
+ /* Restore LR */
+ mtlr r0
+ blr
+
/*
* Check whether an HDSI is an HPTE not found fault or something else.
* If it is an HPTE not found fault that is due to the guest accessing