From: Simon Guo <wei.guo.si...@gmail.com>
Currently kernel doesn't use transaction memory.
And there is an issue for privilege guest that:
tbegin/tsuspend/tresume/tabort TM instructions can impact MSR TM bits
without trap into PR host. So following code will lead to a false mfmsr
result:
tbegin <- MSR bits update to Transaction active.
beq <- failover handler branch
mfmsr <- still read MSR bits from magic page with
transaction inactive.
It is not an issue for non-privilege guest since its mfmsr is not patched
with magic page and will always trap into PR host.
This patch will always fail tbegin attempt for privilege guest, so that
the above issue is prevented. It is benign since currently (guest) kernel
doesn't initiate a transaction.
Test case:
https://github.com/justdoitqd/publicFiles/blob/master/test_tbegin_pr.c
Signed-off-by: Simon Guo <wei.guo.si...@gmail.com>
---
arch/powerpc/include/asm/kvm_book3s.h | 1 +
arch/powerpc/kvm/book3s_emulate.c | 34 ++++++++++++++++++++++++++++++++++
arch/powerpc/kvm/book3s_pr.c | 11 ++++++++++-
3 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h
b/arch/powerpc/include/asm/kvm_book3s.h
index d8dbfa5..524cd82 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -257,6 +257,7 @@ extern void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu,
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
void kvmppc_save_tm_pr(struct kvm_vcpu *vcpu);
void kvmppc_restore_tm_pr(struct kvm_vcpu *vcpu);
+void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu);
#endif
extern int kvm_irq_bypass;
diff --git a/arch/powerpc/kvm/book3s_emulate.c
b/arch/powerpc/kvm/book3s_emulate.c
index c2836330..1eb1900 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -23,6 +23,7 @@
#include <asm/reg.h>
#include <asm/switch_to.h>
#include <asm/time.h>
+#include <asm/tm.h>
#include "book3s.h"
#define OP_19_XOP_RFID 18
@@ -47,6 +48,8 @@
#define OP_31_XOP_EIOIO 854
#define OP_31_XOP_SLBMFEE 915
+#define OP_31_XOP_TBEGIN 654
+
/* DCBZ is actually 1014, but we patch it to 1010 so we get a trap */
#define OP_31_XOP_DCBZ 1010
@@ -360,6 +363,37 @@ int kvmppc_core_emulate_op_pr(struct kvm_run *run, struct
kvm_vcpu *vcpu,
break;
}
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+ case OP_31_XOP_TBEGIN:
+ {
+ if (!(kvmppc_get_msr(vcpu) & MSR_PR)) {
+ preempt_disable();
+ vcpu->arch.cr = (CR0_TBEGIN_FAILURE |
+ (vcpu->arch.cr & ~(CR0_MASK << CR0_SHIFT)));
+
+ vcpu->arch.texasr = (TEXASR_FS | TEXASR_EX |
+ (((u64)(TM_CAUSE_EMULATE |
TM_CAUSE_PERSISTENT))
+ << TEXASR_FC_LG));
+
+ if ((inst >> 21) & 0x1)
+ vcpu->arch.texasr |= TEXASR_ROT;
+
+ if (kvmppc_get_msr(vcpu) & MSR_PR)
+ vcpu->arch.texasr |= TEXASR_PR;
+
+ if (kvmppc_get_msr(vcpu) & MSR_HV)
+ vcpu->arch.texasr |= TEXASR_HV;
+
+ vcpu->arch.tfhar = kvmppc_get_pc(vcpu) + 4;
+ vcpu->arch.tfiar = kvmppc_get_pc(vcpu);
+
+ kvmppc_restore_tm_sprs(vcpu);
+ preempt_enable();
+ } else
+ emulated = EMULATE_FAIL;
+ break;
+ }
+#endif
default:
emulated = EMULATE_FAIL;
}
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index c35bd02..a26f4db 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -255,7 +255,7 @@ static inline void kvmppc_save_tm_sprs(struct kvm_vcpu
*vcpu)
tm_disable();
}
-static inline void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu)
+inline void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu)
{
tm_enable();
mtspr(SPRN_TFHAR, vcpu->arch.tfhar);
@@ -447,6 +447,15 @@ static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
(PVR_VER(guest_pvr) == PVR_970GX))
smsr |= MSR_HV;
#endif
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+ /*
+ * in guest privileged state, we want to fail all TM transactions.
+ * So disable MSR TM bit so that all tbegin. will be able to be
+ * trapped into host.
+ */
+ if (!(guest_msr & MSR_PR))
+ smsr &= ~MSR_TM;
+#endif
vcpu->arch.shadow_msr = smsr;
}
--
1.8.3.1
