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* [PATCH] powerpc/kvm: don't crash on missing rng, and use darn
@ 2022-06-22 10:54 ` Jason A. Donenfeld
  0 siblings, 0 replies; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-06-22 10:54 UTC (permalink / raw)
  To: linuxppc-dev, linux-kernel; +Cc: Jason A. Donenfeld, stable, Michael Ellerman

On POWER8 systems that don't have ibm,power-rng available, a guest that
ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will
dereference a NULL pointer. And on machines with darn instead of
ibm,power-rng, H_RANDOM won't work at all.

This patch kills two birds with one stone, by routing H_RANDOM calls to
ppc_md.get_random_seed, and doing the real mode check inside of it.

Cc: stable@vger.kernel.org # v4.1+
Cc: Michael Ellerman <mpe@ellerman.id.au>
Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

This patch must be applied ontop of:
1) https://github.com/linuxppc/linux/commit/f3eac426657d985b97c92fa5f7ae1d43f04721f3
2) https://lore.kernel.org/all/20220622102532.173393-1-Jason@zx2c4.com/


 arch/powerpc/include/asm/archrandom.h |  5 ----
 arch/powerpc/kvm/book3s_hv_builtin.c  |  5 ++--
 arch/powerpc/platforms/powernv/rng.c  | 33 +++++++--------------------
 3 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
index 11d4815841ab..3af27bb84a3d 100644
--- a/arch/powerpc/include/asm/archrandom.h
+++ b/arch/powerpc/include/asm/archrandom.h
@@ -38,12 +38,7 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 #endif /* CONFIG_ARCH_RANDOM */
 
 #ifdef CONFIG_PPC_POWERNV
-int pnv_hwrng_present(void);
 int pnv_get_random_long(unsigned long *v);
-int pnv_get_random_real_mode(unsigned long *v);
-#else
-static inline int pnv_hwrng_present(void) { return 0; }
-static inline int pnv_get_random_real_mode(unsigned long *v) { return 0; }
 #endif
 
 #endif /* _ASM_POWERPC_ARCHRANDOM_H */
diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 799d40c2ab4f..1c6672826db5 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -176,13 +176,14 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
 
 int kvmppc_hwrng_present(void)
 {
-	return pnv_hwrng_present();
+	return ppc_md.get_random_seed != NULL;
 }
 EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
 
 long kvmppc_rm_h_random(struct kvm_vcpu *vcpu)
 {
-	if (pnv_get_random_real_mode(&vcpu->arch.regs.gpr[4]))
+	if (ppc_md.get_random_seed &&
+	    ppc_md.get_random_seed(&vcpu->arch.regs.gpr[4]))
 		return H_SUCCESS;
 
 	return H_HARDWARE;
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 868bb9777425..c748567cd47e 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -29,15 +29,6 @@ struct pnv_rng {
 
 static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng);
 
-int pnv_hwrng_present(void)
-{
-	struct pnv_rng *rng;
-
-	rng = get_cpu_var(pnv_rng);
-	put_cpu_var(rng);
-	return rng != NULL;
-}
-
 static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
 {
 	unsigned long parity;
@@ -58,17 +49,6 @@ static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
 	return val;
 }
 
-int pnv_get_random_real_mode(unsigned long *v)
-{
-	struct pnv_rng *rng;
-
-	rng = raw_cpu_read(pnv_rng);
-
-	*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
-
-	return 1;
-}
-
 static int pnv_get_random_darn(unsigned long *v)
 {
 	unsigned long val;
@@ -105,11 +85,14 @@ int pnv_get_random_long(unsigned long *v)
 {
 	struct pnv_rng *rng;
 
-	rng = get_cpu_var(pnv_rng);
-
-	*v = rng_whiten(rng, in_be64(rng->regs));
-
-	put_cpu_var(rng);
+	if (mfmsr() & MSR_DR) {
+		rng = raw_cpu_read(pnv_rng);
+		*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
+	} else {
+		rng = get_cpu_var(pnv_rng);
+		*v = rng_whiten(rng, in_be64(rng->regs));
+		put_cpu_var(rng);
+	}
 
 	return 1;
 }
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH] powerpc/kvm: don't crash on missing rng, and use darn
@ 2022-06-22 10:54 ` Jason A. Donenfeld
  0 siblings, 0 replies; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-06-22 10:54 UTC (permalink / raw)
  To: linuxppc-dev, linux-kernel; +Cc: Jason A. Donenfeld, stable

On POWER8 systems that don't have ibm,power-rng available, a guest that
ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will
dereference a NULL pointer. And on machines with darn instead of
ibm,power-rng, H_RANDOM won't work at all.

This patch kills two birds with one stone, by routing H_RANDOM calls to
ppc_md.get_random_seed, and doing the real mode check inside of it.

Cc: stable@vger.kernel.org # v4.1+
Cc: Michael Ellerman <mpe@ellerman.id.au>
Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

This patch must be applied ontop of:
1) https://github.com/linuxppc/linux/commit/f3eac426657d985b97c92fa5f7ae1d43f04721f3
2) https://lore.kernel.org/all/20220622102532.173393-1-Jason@zx2c4.com/


 arch/powerpc/include/asm/archrandom.h |  5 ----
 arch/powerpc/kvm/book3s_hv_builtin.c  |  5 ++--
 arch/powerpc/platforms/powernv/rng.c  | 33 +++++++--------------------
 3 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
index 11d4815841ab..3af27bb84a3d 100644
--- a/arch/powerpc/include/asm/archrandom.h
+++ b/arch/powerpc/include/asm/archrandom.h
@@ -38,12 +38,7 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 #endif /* CONFIG_ARCH_RANDOM */
 
 #ifdef CONFIG_PPC_POWERNV
-int pnv_hwrng_present(void);
 int pnv_get_random_long(unsigned long *v);
-int pnv_get_random_real_mode(unsigned long *v);
-#else
-static inline int pnv_hwrng_present(void) { return 0; }
-static inline int pnv_get_random_real_mode(unsigned long *v) { return 0; }
 #endif
 
 #endif /* _ASM_POWERPC_ARCHRANDOM_H */
diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
index 799d40c2ab4f..1c6672826db5 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -176,13 +176,14 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
 
 int kvmppc_hwrng_present(void)
 {
-	return pnv_hwrng_present();
+	return ppc_md.get_random_seed != NULL;
 }
 EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
 
 long kvmppc_rm_h_random(struct kvm_vcpu *vcpu)
 {
-	if (pnv_get_random_real_mode(&vcpu->arch.regs.gpr[4]))
+	if (ppc_md.get_random_seed &&
+	    ppc_md.get_random_seed(&vcpu->arch.regs.gpr[4]))
 		return H_SUCCESS;
 
 	return H_HARDWARE;
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 868bb9777425..c748567cd47e 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -29,15 +29,6 @@ struct pnv_rng {
 
 static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng);
 
-int pnv_hwrng_present(void)
-{
-	struct pnv_rng *rng;
-
-	rng = get_cpu_var(pnv_rng);
-	put_cpu_var(rng);
-	return rng != NULL;
-}
-
 static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
 {
 	unsigned long parity;
@@ -58,17 +49,6 @@ static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
 	return val;
 }
 
-int pnv_get_random_real_mode(unsigned long *v)
-{
-	struct pnv_rng *rng;
-
-	rng = raw_cpu_read(pnv_rng);
-
-	*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
-
-	return 1;
-}
-
 static int pnv_get_random_darn(unsigned long *v)
 {
 	unsigned long val;
@@ -105,11 +85,14 @@ int pnv_get_random_long(unsigned long *v)
 {
 	struct pnv_rng *rng;
 
-	rng = get_cpu_var(pnv_rng);
-
-	*v = rng_whiten(rng, in_be64(rng->regs));
-
-	put_cpu_var(rng);
+	if (mfmsr() & MSR_DR) {
+		rng = raw_cpu_read(pnv_rng);
+		*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
+	} else {
+		rng = get_cpu_var(pnv_rng);
+		*v = rng_whiten(rng, in_be64(rng->regs));
+		put_cpu_var(rng);
+	}
 
 	return 1;
 }
-- 
2.35.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/kvm: don't crash on missing rng, and use darn
  2022-06-22 10:54 ` Jason A. Donenfeld
  (?)
@ 2022-06-24 13:43 ` Fabiano Rosas
  2022-06-24 14:14   ` Jason A. Donenfeld
  -1 siblings, 1 reply; 4+ messages in thread
From: Fabiano Rosas @ 2022-06-24 13:43 UTC (permalink / raw)
  To: Jason A. Donenfeld, linuxppc-dev, linux-kernel; +Cc: Jason A. Donenfeld, stable

"Jason A. Donenfeld" <Jason@zx2c4.com> writes:

> On POWER8 systems that don't have ibm,power-rng available, a guest that
> ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will
> dereference a NULL pointer. And on machines with darn instead of
> ibm,power-rng, H_RANDOM won't work at all.
>
> This patch kills two birds with one stone, by routing H_RANDOM calls to
> ppc_md.get_random_seed, and doing the real mode check inside of it.
>
> Cc: stable@vger.kernel.org # v4.1+
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>
> This patch must be applied ontop of:
> 1) https://github.com/linuxppc/linux/commit/f3eac426657d985b97c92fa5f7ae1d43f04721f3
> 2) https://lore.kernel.org/all/20220622102532.173393-1-Jason@zx2c4.com/
>
>
>  arch/powerpc/include/asm/archrandom.h |  5 ----
>  arch/powerpc/kvm/book3s_hv_builtin.c  |  5 ++--
>  arch/powerpc/platforms/powernv/rng.c  | 33 +++++++--------------------
>  3 files changed, 11 insertions(+), 32 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
> index 11d4815841ab..3af27bb84a3d 100644
> --- a/arch/powerpc/include/asm/archrandom.h
> +++ b/arch/powerpc/include/asm/archrandom.h
> @@ -38,12 +38,7 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
>  #endif /* CONFIG_ARCH_RANDOM */
>
>  #ifdef CONFIG_PPC_POWERNV
> -int pnv_hwrng_present(void);
>  int pnv_get_random_long(unsigned long *v);
> -int pnv_get_random_real_mode(unsigned long *v);
> -#else
> -static inline int pnv_hwrng_present(void) { return 0; }
> -static inline int pnv_get_random_real_mode(unsigned long *v) { return 0; }
>  #endif
>
>  #endif /* _ASM_POWERPC_ARCHRANDOM_H */
> diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
> index 799d40c2ab4f..1c6672826db5 100644
> --- a/arch/powerpc/kvm/book3s_hv_builtin.c
> +++ b/arch/powerpc/kvm/book3s_hv_builtin.c
> @@ -176,13 +176,14 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
>
>  int kvmppc_hwrng_present(void)
>  {
> -	return pnv_hwrng_present();
> +	return ppc_md.get_random_seed != NULL;
>  }
>  EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
>
>  long kvmppc_rm_h_random(struct kvm_vcpu *vcpu)
>  {
> -	if (pnv_get_random_real_mode(&vcpu->arch.regs.gpr[4]))
> +	if (ppc_md.get_random_seed &&
> +	    ppc_md.get_random_seed(&vcpu->arch.regs.gpr[4]))
>  		return H_SUCCESS;

This is the same as arch_get_random_seed_long, perhaps you could use it
instead.

Otherwise, the archrandom.h include is not needed anymore and could be
replaced with #include <asm/machdep.h> for ppc_md.

>
>  	return H_HARDWARE;
> diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
> index 868bb9777425..c748567cd47e 100644
> --- a/arch/powerpc/platforms/powernv/rng.c
> +++ b/arch/powerpc/platforms/powernv/rng.c
> @@ -29,15 +29,6 @@ struct pnv_rng {
>
>  static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng);
>
> -int pnv_hwrng_present(void)
> -{
> -	struct pnv_rng *rng;
> -
> -	rng = get_cpu_var(pnv_rng);
> -	put_cpu_var(rng);
> -	return rng != NULL;
> -}
> -
>  static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
>  {
>  	unsigned long parity;
> @@ -58,17 +49,6 @@ static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
>  	return val;
>  }
>
> -int pnv_get_random_real_mode(unsigned long *v)
> -{
> -	struct pnv_rng *rng;
> -
> -	rng = raw_cpu_read(pnv_rng);
> -
> -	*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
> -
> -	return 1;
> -}
> -
>  static int pnv_get_random_darn(unsigned long *v)
>  {
>  	unsigned long val;
> @@ -105,11 +85,14 @@ int pnv_get_random_long(unsigned long *v)
>  {
>  	struct pnv_rng *rng;
>
> -	rng = get_cpu_var(pnv_rng);
> -
> -	*v = rng_whiten(rng, in_be64(rng->regs));
> -
> -	put_cpu_var(rng);
> +	if (mfmsr() & MSR_DR) {
> +		rng = raw_cpu_read(pnv_rng);
> +		*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
> +	} else {
> +		rng = get_cpu_var(pnv_rng);
> +		*v = rng_whiten(rng, in_be64(rng->regs));
> +		put_cpu_var(rng);
> +	}
>
>  	return 1;
>  }

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/kvm: don't crash on missing rng, and use darn
  2022-06-24 13:43 ` Fabiano Rosas
@ 2022-06-24 14:14   ` Jason A. Donenfeld
  0 siblings, 0 replies; 4+ messages in thread
From: Jason A. Donenfeld @ 2022-06-24 14:14 UTC (permalink / raw)
  To: Fabiano Rosas; +Cc: linuxppc-dev, LKML, stable

Hi Fabiano,

On Fri, Jun 24, 2022 at 3:43 PM Fabiano Rosas <farosas@linux.ibm.com> wrote:
>
> "Jason A. Donenfeld" <Jason@zx2c4.com> writes:
>
> > On POWER8 systems that don't have ibm,power-rng available, a guest that
> > ignores the KVM_CAP_PPC_HWRNG flag and calls H_RANDOM anyway will
> > dereference a NULL pointer. And on machines with darn instead of
> > ibm,power-rng, H_RANDOM won't work at all.
> >
> > This patch kills two birds with one stone, by routing H_RANDOM calls to
> > ppc_md.get_random_seed, and doing the real mode check inside of it.
> >
> > Cc: stable@vger.kernel.org # v4.1+
> > Cc: Michael Ellerman <mpe@ellerman.id.au>
> > Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> > ---
> >
> > This patch must be applied ontop of:
> > 1) https://github.com/linuxppc/linux/commit/f3eac426657d985b97c92fa5f7ae1d43f04721f3
> > 2) https://lore.kernel.org/all/20220622102532.173393-1-Jason@zx2c4.com/
> >
> >
> >  arch/powerpc/include/asm/archrandom.h |  5 ----
> >  arch/powerpc/kvm/book3s_hv_builtin.c  |  5 ++--
> >  arch/powerpc/platforms/powernv/rng.c  | 33 +++++++--------------------
> >  3 files changed, 11 insertions(+), 32 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
> > index 11d4815841ab..3af27bb84a3d 100644
> > --- a/arch/powerpc/include/asm/archrandom.h
> > +++ b/arch/powerpc/include/asm/archrandom.h
> > @@ -38,12 +38,7 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
> >  #endif /* CONFIG_ARCH_RANDOM */
> >
> >  #ifdef CONFIG_PPC_POWERNV
> > -int pnv_hwrng_present(void);
> >  int pnv_get_random_long(unsigned long *v);
> > -int pnv_get_random_real_mode(unsigned long *v);
> > -#else
> > -static inline int pnv_hwrng_present(void) { return 0; }
> > -static inline int pnv_get_random_real_mode(unsigned long *v) { return 0; }
> >  #endif
> >
> >  #endif /* _ASM_POWERPC_ARCHRANDOM_H */
> > diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
> > index 799d40c2ab4f..1c6672826db5 100644
> > --- a/arch/powerpc/kvm/book3s_hv_builtin.c
> > +++ b/arch/powerpc/kvm/book3s_hv_builtin.c
> > @@ -176,13 +176,14 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
> >
> >  int kvmppc_hwrng_present(void)
> >  {
> > -     return pnv_hwrng_present();
> > +     return ppc_md.get_random_seed != NULL;
> >  }
> >  EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
> >
> >  long kvmppc_rm_h_random(struct kvm_vcpu *vcpu)
> >  {
> > -     if (pnv_get_random_real_mode(&vcpu->arch.regs.gpr[4]))
> > +     if (ppc_md.get_random_seed &&
> > +         ppc_md.get_random_seed(&vcpu->arch.regs.gpr[4]))
> >               return H_SUCCESS;
>
> This is the same as arch_get_random_seed_long, perhaps you could use it
> instead.

Sure, why not. Will send a v2.

Jason

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-06-24 14:15 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-06-22 10:54 [PATCH] powerpc/kvm: don't crash on missing rng, and use darn Jason A. Donenfeld
2022-06-22 10:54 ` Jason A. Donenfeld
2022-06-24 13:43 ` Fabiano Rosas
2022-06-24 14:14   ` Jason A. Donenfeld

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