Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
Alexander Graf ag...@suse.de writes: --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -25,7 +25,6 @@ #ifdef CONFIG_8xx #include asm/reg_8xx.h #endif /* CONFIG_8xx */ -#include asm/bug.h #define MSR_SF_LG 63 /* Enable 64 bit mode */ #define MSR_ISF_LG 61 /* Interrupt 64b mode valid on 630 */ @@ -1210,12 +1209,6 @@ static inline unsigned long mfvtb (void) if (cpu_has_feature(CPU_FTR_ARCH_207S)) return mfspr(SPRN_VTB); #endif - /* -* The above mfspr will be a no-op on anything before Power8 -* That can result in random values returned. We need to -* capture that. -*/ - BUG(); return 0; } (i missed CCing aneesh on this mail in reply to the build robot, so inserting the same reply here) the only place that calls it also does the cpu_has_feature() check and returns 0 ifndef CONFIG_PPC_BOOK3S_64 or !cpu_has_feature(). Looking get_vtb (the only caller) and the places it's called (as well as PowerISA 2.07) I think in the emulation code we're missing invoking the system privileged instruction error handler as the VTB SPR has spr bit 0 set to 1 (page 107 of PowerISA 2.07, mfspr docs). That being said... any guest sholud do the cpu_has_feature check themselves, so this probably isn't an issue in the real world. Certainly the host really shouldn't BUG() for what is really a guest issue (actually.. this would be a good DoS attack on Power8 host). Reviewed-by: Stewart Smith stew...@linux.vnet.ibm.com -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
On 05.06.14 14:08, Aneesh Kumar K.V wrote: virtual time base register is a per VM, per cpu register that needs to be saved and restored on vm exit and entry. Writing to VTB is not allowed in the privileged mode. Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com For some reason BUG() doesn't always trigger the execution stops here logic in gcc. So I've squashed this patch into yours. Alex diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 3e7085d..99de6ad 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1206,6 +1206,7 @@ static inline unsigned long mfvtb (void) * capture that. */ BUG(); +return 0; } #ifdef __powerpc64__ -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
Alexander Graf ag...@suse.de writes: On 05.06.14 14:08, Aneesh Kumar K.V wrote: virtual time base register is a per VM, per cpu register that needs to be saved and restored on vm exit and entry. Writing to VTB is not allowed in the privileged mode. Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com For some reason BUG() doesn't always trigger the execution stops here logic in gcc. So I've squashed this patch into yours. Alex diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 3e7085d..99de6ad 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h @@ -1206,6 +1206,7 @@ static inline unsigned long mfvtb (void) * capture that. */ BUG(); +return 0; } #ifdef __powerpc64__ you can then drop the include header change. ie, #include asm/bug.h -aneesh -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
On 05.06.14 14:08, Aneesh Kumar K.V wrote:
virtual time base register is a per VM, per cpu register that needs
to be saved and restored on vm exit and entry. Writing to VTB is not
allowed in the privileged mode.
Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/include/asm/reg.h | 15 +++
arch/powerpc/include/asm/time.h | 9 +
arch/powerpc/kvm/book3s.c | 6 ++
arch/powerpc/kvm/book3s_emulate.c | 3 +++
arch/powerpc/kvm/book3s_hv.c| 6 --
arch/powerpc/kvm/book3s_pr.c| 3 ++-
7 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h
b/arch/powerpc/include/asm/kvm_host.h
index 4a58731a0a72..bd3caeaeebe1 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -505,6 +505,7 @@ struct kvm_vcpu_arch {
#endif
/* Time base value when we entered the guest */
u64 entry_tb;
+ u64 entry_vtb;
u32 tcr;
ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
u32 ivor[64];
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 4852bcf270f3..3e7085d8af90 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -25,6 +25,7 @@
#ifdef CONFIG_8xx
#include asm/reg_8xx.h
#endif /* CONFIG_8xx */
+#include asm/bug.h
#define MSR_SF_LG 63 /* Enable 64 bit mode */
#define MSR_ISF_LG61 /* Interrupt 64b mode valid on 630 */
@@ -1193,6 +1194,20 @@
: r ((unsigned long)(v)) \
: memory)
+static inline unsigned long mfvtb (void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_ARCH_207S))
+ return mfspr(SPRN_VTB);
+#endif
+ /*
+* The above mfspr will be a no-op on anything before Power8
+* That can result in random values returned. We need to
+* capture that.
+*/
+ BUG();
+}
+
#ifdef __powerpc64__
#if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
#define mftb()({unsigned long rval;
\
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 1d428e6007ca..03cbada59d3a 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -102,6 +102,15 @@ static inline u64 get_rtc(void)
return (u64)hi * 10 + lo;
}
+static inline u64 get_vtb(void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_ARCH_207S))
+ return mfvtb();
+#endif
+ return 0;
+}
+
#ifdef CONFIG_PPC64
static inline u64 get_tb(void)
{
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 52c654dbd41a..ae43e4178ecd 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -646,6 +646,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
val = get_reg_val(reg-id, vcpu-arch.bescr);
break;
+ case KVM_REG_PPC_VTB:
+ val = get_reg_val(reg-id, vcpu-arch.vtb);
+ break;
default:
r = -EINVAL;
break;
@@ -750,6 +753,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
vcpu-arch.bescr = set_reg_val(reg-id, val);
break;
+ case KVM_REG_PPC_VTB:
+ vcpu-arch.vtb = set_reg_val(reg-id, val);
+ break;
default:
r = -EINVAL;
break;
diff --git a/arch/powerpc/kvm/book3s_emulate.c
b/arch/powerpc/kvm/book3s_emulate.c
index 3565e775b61b..1bb16a59dcbc 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int
sprn, ulong *spr_val
*/
*spr_val = vcpu-arch.spurr;
break;
+ case SPRN_VTB:
+ *spr_val = vcpu-arch.vtb;
Doesn't this mean that vtb can be the same 2 when the guest reads it 2
times in a row without getting preempted?
Alex
+ break;
case SPRN_GQR0:
case SPRN_GQR1:
case SPRN_GQR2:
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index aba05bbb3e74..f6ac58336b3f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -897,9 +897,6 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64
id,
case KVM_REG_PPC_IC:
*val = get_reg_val(id, vcpu-arch.ic);
break;
-
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
Alexander Graf ag...@suse.de writes:
On 05.06.14 14:08, Aneesh Kumar K.V wrote:
virtual time base register is a per VM, per cpu register that needs
to be saved and restored on vm exit and entry. Writing to VTB is not
allowed in the privileged mode.
Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/include/asm/reg.h | 15 +++
arch/powerpc/include/asm/time.h | 9 +
arch/powerpc/kvm/book3s.c | 6 ++
arch/powerpc/kvm/book3s_emulate.c | 3 +++
arch/powerpc/kvm/book3s_hv.c| 6 --
arch/powerpc/kvm/book3s_pr.c| 3 ++-
7 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h
b/arch/powerpc/include/asm/kvm_host.h
index 4a58731a0a72..bd3caeaeebe1 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -505,6 +505,7 @@ struct kvm_vcpu_arch {
#endif
/* Time base value when we entered the guest */
u64 entry_tb;
+u64 entry_vtb;
u32 tcr;
ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
u32 ivor[64];
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 4852bcf270f3..3e7085d8af90 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -25,6 +25,7 @@
#ifdef CONFIG_8xx
#include asm/reg_8xx.h
#endif /* CONFIG_8xx */
+#include asm/bug.h
#define MSR_SF_LG 63 /* Enable 64 bit mode */
#define MSR_ISF_LG 61 /* Interrupt 64b mode valid on 630 */
@@ -1193,6 +1194,20 @@
: r ((unsigned long)(v)) \
: memory)
+static inline unsigned long mfvtb (void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+if (cpu_has_feature(CPU_FTR_ARCH_207S))
+return mfspr(SPRN_VTB);
+#endif
+/*
+ * The above mfspr will be a no-op on anything before Power8
+ * That can result in random values returned. We need to
+ * capture that.
+ */
+BUG();
+}
+
#ifdef __powerpc64__
#if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
#define mftb() ({unsigned long rval;
\
diff --git a/arch/powerpc/include/asm/time.h
b/arch/powerpc/include/asm/time.h
index 1d428e6007ca..03cbada59d3a 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -102,6 +102,15 @@ static inline u64 get_rtc(void)
return (u64)hi * 10 + lo;
}
+static inline u64 get_vtb(void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+if (cpu_has_feature(CPU_FTR_ARCH_207S))
+return mfvtb();
+#endif
+return 0;
+}
+
#ifdef CONFIG_PPC64
static inline u64 get_tb(void)
{
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 52c654dbd41a..ae43e4178ecd 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -646,6 +646,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
val = get_reg_val(reg-id, vcpu-arch.bescr);
break;
+case KVM_REG_PPC_VTB:
+val = get_reg_val(reg-id, vcpu-arch.vtb);
+break;
default:
r = -EINVAL;
break;
@@ -750,6 +753,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
vcpu-arch.bescr = set_reg_val(reg-id, val);
break;
+case KVM_REG_PPC_VTB:
+vcpu-arch.vtb = set_reg_val(reg-id, val);
+break;
default:
r = -EINVAL;
break;
diff --git a/arch/powerpc/kvm/book3s_emulate.c
b/arch/powerpc/kvm/book3s_emulate.c
index 3565e775b61b..1bb16a59dcbc 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu,
int sprn, ulong *spr_val
*/
*spr_val = vcpu-arch.spurr;
break;
+case SPRN_VTB:
+*spr_val = vcpu-arch.vtb;
Doesn't this mean that vtb can be the same 2 when the guest reads it 2
times in a row without getting preempted?
But a mfspr will result in VM exit and that would make sure we
update vcpu-arch.vtb with the correct value.
-aneesh
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Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
On 05.06.14 17:50, Aneesh Kumar K.V wrote:
Alexander Graf ag...@suse.de writes:
On 05.06.14 14:08, Aneesh Kumar K.V wrote:
virtual time base register is a per VM, per cpu register that needs
to be saved and restored on vm exit and entry. Writing to VTB is not
allowed in the privileged mode.
Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com
---
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/include/asm/reg.h | 15 +++
arch/powerpc/include/asm/time.h | 9 +
arch/powerpc/kvm/book3s.c | 6 ++
arch/powerpc/kvm/book3s_emulate.c | 3 +++
arch/powerpc/kvm/book3s_hv.c| 6 --
arch/powerpc/kvm/book3s_pr.c| 3 ++-
7 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_host.h
b/arch/powerpc/include/asm/kvm_host.h
index 4a58731a0a72..bd3caeaeebe1 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -505,6 +505,7 @@ struct kvm_vcpu_arch {
#endif
/* Time base value when we entered the guest */
u64 entry_tb;
+ u64 entry_vtb;
u32 tcr;
ulong tsr; /* we need to perform set/clr_bits() which requires ulong */
u32 ivor[64];
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 4852bcf270f3..3e7085d8af90 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -25,6 +25,7 @@
#ifdef CONFIG_8xx
#include asm/reg_8xx.h
#endif /* CONFIG_8xx */
+#include asm/bug.h
#define MSR_SF_LG 63 /* Enable 64 bit mode */
#define MSR_ISF_LG 61 /* Interrupt 64b mode valid on 630 */
@@ -1193,6 +1194,20 @@
: r ((unsigned long)(v)) \
: memory)
+static inline unsigned long mfvtb (void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_ARCH_207S))
+ return mfspr(SPRN_VTB);
+#endif
+ /*
+* The above mfspr will be a no-op on anything before Power8
+* That can result in random values returned. We need to
+* capture that.
+*/
+ BUG();
+}
+
#ifdef __powerpc64__
#if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
#define mftb() ({unsigned long rval;
\
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 1d428e6007ca..03cbada59d3a 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -102,6 +102,15 @@ static inline u64 get_rtc(void)
return (u64)hi * 10 + lo;
}
+static inline u64 get_vtb(void)
+{
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (cpu_has_feature(CPU_FTR_ARCH_207S))
+ return mfvtb();
+#endif
+ return 0;
+}
+
#ifdef CONFIG_PPC64
static inline u64 get_tb(void)
{
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 52c654dbd41a..ae43e4178ecd 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -646,6 +646,9 @@ int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
val = get_reg_val(reg-id, vcpu-arch.bescr);
break;
+ case KVM_REG_PPC_VTB:
+ val = get_reg_val(reg-id, vcpu-arch.vtb);
+ break;
default:
r = -EINVAL;
break;
@@ -750,6 +753,9 @@ int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
struct kvm_one_reg *reg)
case KVM_REG_PPC_BESCR:
vcpu-arch.bescr = set_reg_val(reg-id, val);
break;
+ case KVM_REG_PPC_VTB:
+ vcpu-arch.vtb = set_reg_val(reg-id, val);
+ break;
default:
r = -EINVAL;
break;
diff --git a/arch/powerpc/kvm/book3s_emulate.c
b/arch/powerpc/kvm/book3s_emulate.c
index 3565e775b61b..1bb16a59dcbc 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int
sprn, ulong *spr_val
*/
*spr_val = vcpu-arch.spurr;
break;
+ case SPRN_VTB:
+ *spr_val = vcpu-arch.vtb;
Doesn't this mean that vtb can be the same 2 when the guest reads it 2
times in a row without getting preempted?
But a mfspr will result in VM exit and that would make sure we
update vcpu-arch.vtb with the correct value.
We only call kvmppc_core_vcpu_put_pr() when we context switch away from
KVM, so it won't be updated, no?
Alex
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Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
Alexander Graf ag...@suse.de writes: On 05.06.14 17:50, Aneesh Kumar K.V wrote: Alexander Graf ag...@suse.de writes: On 05.06.14 14:08, Aneesh Kumar K.V wrote: virtual time base register is a per VM, per cpu register that needs to be saved and restored on vm exit and entry. Writing to VTB is not allowed in the privileged mode. Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com ... break; diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 3565e775b61b..1bb16a59dcbc 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val */ *spr_val = vcpu-arch.spurr; break; + case SPRN_VTB: + *spr_val = vcpu-arch.vtb; Doesn't this mean that vtb can be the same 2 when the guest reads it 2 times in a row without getting preempted? But a mfspr will result in VM exit and that would make sure we update vcpu-arch.vtb with the correct value. We only call kvmppc_core_vcpu_put_pr() when we context switch away from KVM, so it won't be updated, no? kvmppc_copy_from_svcpu is also called from VM exit path (book3s_interrupt.S) -aneesh -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
On 05.06.14 19:33, Aneesh Kumar K.V wrote: Alexander Graf ag...@suse.de writes: On 05.06.14 17:50, Aneesh Kumar K.V wrote: Alexander Graf ag...@suse.de writes: On 05.06.14 14:08, Aneesh Kumar K.V wrote: virtual time base register is a per VM, per cpu register that needs to be saved and restored on vm exit and entry. Writing to VTB is not allowed in the privileged mode. Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com ... break; diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 3565e775b61b..1bb16a59dcbc 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val */ *spr_val = vcpu-arch.spurr; break; + case SPRN_VTB: + *spr_val = vcpu-arch.vtb; Doesn't this mean that vtb can be the same 2 when the guest reads it 2 times in a row without getting preempted? But a mfspr will result in VM exit and that would make sure we update vcpu-arch.vtb with the correct value. We only call kvmppc_core_vcpu_put_pr() when we context switch away from KVM, so it won't be updated, no? kvmppc_copy_from_svcpu is also called from VM exit path (book3s_interrupt.S) ... where it will run into this code path: /* * Maybe we were already preempted and synced the svcpu from * our preempt notifiers. Don't bother touching this svcpu then. */ if (!svcpu-in_use) goto out; Alex -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/4] KVM: PPC: BOOK3S: PR: Emulate virtual timebase register
On 06.06.14 00:32, Alexander Graf wrote: On 05.06.14 19:33, Aneesh Kumar K.V wrote: Alexander Graf ag...@suse.de writes: On 05.06.14 17:50, Aneesh Kumar K.V wrote: Alexander Graf ag...@suse.de writes: On 05.06.14 14:08, Aneesh Kumar K.V wrote: virtual time base register is a per VM, per cpu register that needs to be saved and restored on vm exit and entry. Writing to VTB is not allowed in the privileged mode. Signed-off-by: Aneesh Kumar K.V aneesh.ku...@linux.vnet.ibm.com ... break; diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c index 3565e775b61b..1bb16a59dcbc 100644 --- a/arch/powerpc/kvm/book3s_emulate.c +++ b/arch/powerpc/kvm/book3s_emulate.c @@ -577,6 +577,9 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val */ *spr_val = vcpu-arch.spurr; break; +case SPRN_VTB: +*spr_val = vcpu-arch.vtb; Doesn't this mean that vtb can be the same 2 when the guest reads it 2 times in a row without getting preempted? But a mfspr will result in VM exit and that would make sure we update vcpu-arch.vtb with the correct value. We only call kvmppc_core_vcpu_put_pr() when we context switch away from KVM, so it won't be updated, no? kvmppc_copy_from_svcpu is also called from VM exit path (book3s_interrupt.S) ... where it will run into this code path: /* * Maybe we were already preempted and synced the svcpu from * our preempt notifiers. Don't bother touching this svcpu then. */ if (!svcpu-in_use) goto out; Scratch that. We're always calling this on entry/exit, so you're right. Alex -- To unsubscribe from this list: send the line unsubscribe kvm-ppc in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
