Hi Paul,
On Tue, Jan 23, 2018 at 04:42:09PM +1100, Paul Mackerras wrote:
On Thu, Jan 11, 2018 at 06:11:15PM +0800, wei.guo.simon@gmail.com wrote:
quoted
From: Simon Guo <redacted>
HV KVM and PR KVM need different MSR source to indicate whether
treclaim. or trecheckpoint. is necessary.
This patch add new parameter (guest MSR) for these kvmppc_save_tm/
kvmppc_restore_tm() APIs:
- For HV KVM, it is VCPU_MSR
- For PR KVM, it is current host MSR or VCPU_SHADOW_SRR1
This enhancement enables these 2 APIs to be reused by PR KVM later.
And the patch keeps HV KVM logic unchanged.
This patch also reworks kvmppc_save_tm()/kvmppc_restore_tm() to
have a clean ABI: r3 for vcpu and r4 for guest_msr.
Signed-off-by: Simon Guo <redacted>
Question: why do you switch from using HSTATE_HOST_R1 to HSTATE_SCRATCH2
quoted
@@ -42,11 +45,11 @@ _GLOBAL(kvmppc_save_tm)
rldimi r8, r0, MSR_TM_LG, 63-MSR_TM_LG
mtmsrd r8
- ld r5, VCPU_MSR(r9)
- rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
+ rldicl. r4, r4, 64 - MSR_TS_S_LG, 62
beq 1f /* TM not active in guest. */
- std r1, HSTATE_HOST_R1(r13)
+ std r1, HSTATE_SCRATCH2(r13)
... here?
quoted
@@ -166,17 +173,17 @@ _GLOBAL(kvmppc_restore_tm)
* The user may change these outside of a transaction, so they must
* always be context switched.
*/
- ld r5, VCPU_TFHAR(r4)
- ld r6, VCPU_TFIAR(r4)
- ld r7, VCPU_TEXASR(r4)
+ ld r5, VCPU_TFHAR(r3)
+ ld r6, VCPU_TFIAR(r3)
+ ld r7, VCPU_TEXASR(r3)
mtspr SPRN_TFHAR, r5
mtspr SPRN_TFIAR, r6
mtspr SPRN_TEXASR, r7
- ld r5, VCPU_MSR(r4)
+ mr r5, r4
rldicl. r5, r5, 64 - MSR_TS_S_LG, 62
beqlr /* TM not active in guest */
- std r1, HSTATE_HOST_R1(r13)
+ std r1, HSTATE_SCRATCH2(r13)
and here?
Please add a paragraph to the patch description explaining why you are
making that change.
In subsequent patches, kvmppc_save_tm/kvmppc_restore_tm() will be
invoked by wrapper function who setup addtional stack frame and
update R1(then update HSTATE_HOST_R1 with addtional offset). Although
HSTATE_HOST_R1 is now used safely(always PPC_STL before entering
guest and PPC_LL in kvmppc_interrupt_pr()), I worried a future usage
will take an assumption on HSTATE_HOST_R1 value and bring trouble.
As a result, in kvmppc_save_tm/kvmppc_restore_tm() case, I choose
HSTATE_SCRATCH2 to restore the r1. I will update the commit message.
Thanks,
- Simon
Paul.