On Thu, Jan 11, 2018 at 06:11:17PM +0800, wei.guo.simon@gmail.com wrote:
From: Simon Guo <redacted>
Currently _kvmppc_save/restore_tm() APIs can only be invoked from
assembly function. This patch adds C function wrappers for them so
that they can be safely called from C function.
Signed-off-by: Simon Guo <redacted>
[snip]
quoted hunk ↗ jump to hunk
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -126,4 +126,11 @@ unsigned long __init prom_init(unsigned long r3, unsigned long r4,
void _mcount(void);
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip);
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+/* Transaction memory related */
+struct kvm_vcpu;
+void _kvmppc_restore_tm_pr(struct kvm_vcpu *vcpu, u64 guest_msr);
+void _kvmppc_save_tm_pr(struct kvm_vcpu *vcpu, u64 guest_msr);
+#endif
It's not generally necessary to have ifdefs around function
declarations. If the function is never defined because the feature
is not configured in, that is fine.
quoted hunk ↗ jump to hunk
@@ -149,6 +149,58 @@ _GLOBAL(kvmppc_save_tm)
blr
/*
+ * _kvmppc_save_tm() is a wrapper around __kvmppc_save_tm(), so that it can
+ * be invoked from C function by PR KVM only.
+ */
+_GLOBAL(_kvmppc_save_tm_pr)
+ mflr r5
+ std r5, PPC_LR_STKOFF(r1)
+ stdu r1, -SWITCH_FRAME_SIZE(r1)
+ SAVE_NVGPRS(r1)
+
+ /* save MSR since TM/math bits might be impacted
+ * by __kvmppc_save_tm().
+ */
+ mfmsr r5
+ SAVE_GPR(5, r1)
+
+ /* also save DSCR/CR so that it can be recovered later */
+ mfspr r6, SPRN_DSCR
+ SAVE_GPR(6, r1)
+
+ mfcr r7
+ stw r7, _CCR(r1)
+
+ /* allocate stack frame for __kvmppc_save_tm since
+ * it will save LR into its stackframe and we don't
+ * want to corrupt _kvmppc_save_tm_pr's.
+ */
+ stdu r1, -PPC_MIN_STKFRM(r1)
You don't need to do this. In the PowerPC ELF ABI, functions always
save their LR (i.e. their return address) in their *caller's* stack
frame, not their own. You have established a stack frame for
_kvmppc_save_tm_pr above, and that is sufficient. Same comment
applies for _kvmppc_restore_tm_pr.
Paul.