diff mbox

[v3] KVM: PPC: Book3S PR: Do not fail emulation with mtspr/mfspr for unknown SPRs

Message ID 1491400731-2492-1-git-send-email-thuth@redhat.com
State Accepted
Headers show

Commit Message

Thomas Huth April 5, 2017, 1:58 p.m. UTC
According to the PowerISA 2.07, mtspr and mfspr should not always
generate an illegal instruction exception when being used with an
undefined SPR, but rather treat the instruction as a NOP or inject a
privilege exception in some cases, too - depending on the SPR number.
Also turn the printk here into a ratelimited print statement, so that
the guest can not flood the dmesg log of the host by issueing lots of
illegal mtspr/mfspr instruction here.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 v3:
 - Make sure that we do not advance the program counter after we've
   already changed it due to injecting a program interrupt

 v2:
 - Inject illegal instruction program interrupt instead of emulation
   assist interrupt (according to the last programming note in section
   6.5.9 of Book III of the PowerISA v2.07)

 arch/powerpc/kvm/book3s_emulate.c | 34 ++++++++++++++++++++++++++--------
 arch/powerpc/kvm/emulate.c        |  8 ++++++++
 2 files changed, 34 insertions(+), 8 deletions(-)

Comments

Thomas Huth April 25, 2017, 7:14 a.m. UTC | #1
On 05.04.2017 15:58, Thomas Huth wrote:
> According to the PowerISA 2.07, mtspr and mfspr should not always
> generate an illegal instruction exception when being used with an
> undefined SPR, but rather treat the instruction as a NOP or inject a
> privilege exception in some cases, too - depending on the SPR number.
> Also turn the printk here into a ratelimited print statement, so that
> the guest can not flood the dmesg log of the host by issueing lots of
> illegal mtspr/mfspr instruction here.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  v3:
>  - Make sure that we do not advance the program counter after we've
>    already changed it due to injecting a program interrupt
> 
>  v2:
>  - Inject illegal instruction program interrupt instead of emulation
>    assist interrupt (according to the last programming note in section
>    6.5.9 of Book III of the PowerISA v2.07)
> 
>  arch/powerpc/kvm/book3s_emulate.c | 34 ++++++++++++++++++++++++++--------
>  arch/powerpc/kvm/emulate.c        |  8 ++++++++
>  2 files changed, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
> index 8359752..68d6898 100644
> --- a/arch/powerpc/kvm/book3s_emulate.c
> +++ b/arch/powerpc/kvm/book3s_emulate.c
> @@ -503,10 +503,18 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
>  		break;
>  unprivileged:
>  	default:
> -		printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn);
> -#ifndef DEBUG_SPR
> -		emulated = EMULATE_FAIL;
> -#endif
> +		pr_info_ratelimited("KVM: invalid SPR write: %d\n", sprn);
> +		if (sprn & 0x10) {
> +			if (kvmppc_get_msr(vcpu) & MSR_PR) {
> +				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
> +				emulated = EMULATE_AGAIN;
> +			}
> +		} else {
> +			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0) {
> +				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> +				emulated = EMULATE_AGAIN;
> +			}
> +		}
>  		break;
>  	}
>  
> @@ -648,10 +656,20 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
>  		break;
>  	default:
>  unprivileged:
> -		printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn);
> -#ifndef DEBUG_SPR
> -		emulated = EMULATE_FAIL;
> -#endif
> +		pr_info_ratelimited("KVM: invalid SPR read: %d\n", sprn);
> +		if (sprn & 0x10) {
> +			if (kvmppc_get_msr(vcpu) & MSR_PR) {
> +				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
> +				emulated = EMULATE_AGAIN;
> +			}
> +		} else {
> +			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0 ||
> +			    sprn == 4 || sprn == 5 || sprn == 6) {
> +				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> +				emulated = EMULATE_AGAIN;
> +			}
> +		}
> +
>  		break;
>  	}
>  
> diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
> index b379146..c873ffe 100644
> --- a/arch/powerpc/kvm/emulate.c
> +++ b/arch/powerpc/kvm/emulate.c
> @@ -259,10 +259,18 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
>  
>  		case OP_31_XOP_MFSPR:
>  			emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt);
> +			if (emulated == EMULATE_AGAIN) {
> +				emulated = EMULATE_DONE;
> +				advance = 0;
> +			}
>  			break;
>  
>  		case OP_31_XOP_MTSPR:
>  			emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs);
> +			if (emulated == EMULATE_AGAIN) {
> +				emulated = EMULATE_DONE;
> +				advance = 0;
> +			}
>  			break;
>  
>  		case OP_31_XOP_TLBSYNC:
> 

Ping!

Paul, does this now look OK for you this way?

 Thomas

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Paul Mackerras April 26, 2017, 1:07 a.m. UTC | #2
On Tue, Apr 25, 2017 at 09:14:01AM +0200, Thomas Huth wrote:
> On 05.04.2017 15:58, Thomas Huth wrote:
> > According to the PowerISA 2.07, mtspr and mfspr should not always
> > generate an illegal instruction exception when being used with an
> > undefined SPR, but rather treat the instruction as a NOP or inject a
> > privilege exception in some cases, too - depending on the SPR number.
> > Also turn the printk here into a ratelimited print statement, so that
> > the guest can not flood the dmesg log of the host by issueing lots of
> > illegal mtspr/mfspr instruction here.
> > 
> > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > ---
> >  v3:
> >  - Make sure that we do not advance the program counter after we've
> >    already changed it due to injecting a program interrupt
> > 
> >  v2:
> >  - Inject illegal instruction program interrupt instead of emulation
> >    assist interrupt (according to the last programming note in section
> >    6.5.9 of Book III of the PowerISA v2.07)
> > 
> >  arch/powerpc/kvm/book3s_emulate.c | 34 ++++++++++++++++++++++++++--------
> >  arch/powerpc/kvm/emulate.c        |  8 ++++++++
> >  2 files changed, 34 insertions(+), 8 deletions(-)
> > 
> > diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
> > index 8359752..68d6898 100644
> > --- a/arch/powerpc/kvm/book3s_emulate.c
> > +++ b/arch/powerpc/kvm/book3s_emulate.c
> > @@ -503,10 +503,18 @@ int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
> >  		break;
> >  unprivileged:
> >  	default:
> > -		printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn);
> > -#ifndef DEBUG_SPR
> > -		emulated = EMULATE_FAIL;
> > -#endif
> > +		pr_info_ratelimited("KVM: invalid SPR write: %d\n", sprn);
> > +		if (sprn & 0x10) {
> > +			if (kvmppc_get_msr(vcpu) & MSR_PR) {
> > +				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
> > +				emulated = EMULATE_AGAIN;
> > +			}
> > +		} else {
> > +			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0) {
> > +				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> > +				emulated = EMULATE_AGAIN;
> > +			}
> > +		}
> >  		break;
> >  	}
> >  
> > @@ -648,10 +656,20 @@ int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
> >  		break;
> >  	default:
> >  unprivileged:
> > -		printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn);
> > -#ifndef DEBUG_SPR
> > -		emulated = EMULATE_FAIL;
> > -#endif
> > +		pr_info_ratelimited("KVM: invalid SPR read: %d\n", sprn);
> > +		if (sprn & 0x10) {
> > +			if (kvmppc_get_msr(vcpu) & MSR_PR) {
> > +				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
> > +				emulated = EMULATE_AGAIN;
> > +			}
> > +		} else {
> > +			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0 ||
> > +			    sprn == 4 || sprn == 5 || sprn == 6) {
> > +				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> > +				emulated = EMULATE_AGAIN;
> > +			}
> > +		}
> > +
> >  		break;
> >  	}
> >  
> > diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
> > index b379146..c873ffe 100644
> > --- a/arch/powerpc/kvm/emulate.c
> > +++ b/arch/powerpc/kvm/emulate.c
> > @@ -259,10 +259,18 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
> >  
> >  		case OP_31_XOP_MFSPR:
> >  			emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt);
> > +			if (emulated == EMULATE_AGAIN) {
> > +				emulated = EMULATE_DONE;
> > +				advance = 0;
> > +			}
> >  			break;
> >  
> >  		case OP_31_XOP_MTSPR:
> >  			emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs);
> > +			if (emulated == EMULATE_AGAIN) {
> > +				emulated = EMULATE_DONE;
> > +				advance = 0;
> > +			}
> >  			break;
> >  
> >  		case OP_31_XOP_TLBSYNC:
> > 
> 
> Ping!
> 
> Paul, does this now look OK for you this way?

Yes, and I put it in, see commit feafd13c96d6.

Paul.
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diff mbox

Patch

diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 8359752..68d6898 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -503,10 +503,18 @@  int kvmppc_core_emulate_mtspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 		break;
 unprivileged:
 	default:
-		printk(KERN_INFO "KVM: invalid SPR write: %d\n", sprn);
-#ifndef DEBUG_SPR
-		emulated = EMULATE_FAIL;
-#endif
+		pr_info_ratelimited("KVM: invalid SPR write: %d\n", sprn);
+		if (sprn & 0x10) {
+			if (kvmppc_get_msr(vcpu) & MSR_PR) {
+				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
+				emulated = EMULATE_AGAIN;
+			}
+		} else {
+			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0) {
+				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
+				emulated = EMULATE_AGAIN;
+			}
+		}
 		break;
 	}
 
@@ -648,10 +656,20 @@  int kvmppc_core_emulate_mfspr_pr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val
 		break;
 	default:
 unprivileged:
-		printk(KERN_INFO "KVM: invalid SPR read: %d\n", sprn);
-#ifndef DEBUG_SPR
-		emulated = EMULATE_FAIL;
-#endif
+		pr_info_ratelimited("KVM: invalid SPR read: %d\n", sprn);
+		if (sprn & 0x10) {
+			if (kvmppc_get_msr(vcpu) & MSR_PR) {
+				kvmppc_core_queue_program(vcpu, SRR1_PROGPRIV);
+				emulated = EMULATE_AGAIN;
+			}
+		} else {
+			if ((kvmppc_get_msr(vcpu) & MSR_PR) || sprn == 0 ||
+			    sprn == 4 || sprn == 5 || sprn == 6) {
+				kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
+				emulated = EMULATE_AGAIN;
+			}
+		}
+
 		break;
 	}
 
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index b379146..c873ffe 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -259,10 +259,18 @@  int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 
 		case OP_31_XOP_MFSPR:
 			emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt);
+			if (emulated == EMULATE_AGAIN) {
+				emulated = EMULATE_DONE;
+				advance = 0;
+			}
 			break;
 
 		case OP_31_XOP_MTSPR:
 			emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs);
+			if (emulated == EMULATE_AGAIN) {
+				emulated = EMULATE_DONE;
+				advance = 0;
+			}
 			break;
 
 		case OP_31_XOP_TLBSYNC: