[PATCH v4 0/2] powerpc rng cleanups

[PATCH v4 0/2] powerpc rng cleanups

[Jason A. Donenfeld]

These are two small cleanups for -next.

This is meant to be atop
https://lore.kernel.org/all/20220630121654.1939181-1-Jason@zx2c4.com/
which is expected to land first.

v4 fixes up an inversion of thr DR flag.

Jason A. Donenfeld (2):
  powerpc/powernv: rename remaining rng powernv_ functions to pnv_
  powerpc/kvm: don't crash on missing rng, and use darn

 arch/powerpc/include/asm/archrandom.h |  7 +--
 arch/powerpc/kvm/book3s_hv_builtin.c  |  7 +--
 arch/powerpc/platforms/powernv/rng.c  | 66 ++++++++++-----------------
 drivers/char/hw_random/powernv-rng.c  |  2 +-
 4 files changed, 30 insertions(+), 52 deletions(-)

-- 
2.35.1

[PATCH v4 1/2] powerpc/powernv: rename remaining rng powernv_ functions to pnv_

[Jason A. Donenfeld]

The preferred nomenclature is pnv_, not powernv_, but rng.c used
powernv_ for some reason, which isn't consistent with the rest. A recent
commit added a few pnv_ functions to rng.c, making the file a bit of a
mishmash. This commit just replaces the rest of them.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Fixes: f3eac426657 ("powerpc/powernv: wire up rng during setup_arch")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/include/asm/archrandom.h | 10 +++---
 arch/powerpc/kvm/book3s_hv_builtin.c  |  4 +--
 arch/powerpc/platforms/powernv/rng.c  | 44 +++++++++++++--------------
 drivers/char/hw_random/powernv-rng.c  |  2 +-
 4 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
index 9a53e29680f4..11d4815841ab 100644
--- a/arch/powerpc/include/asm/archrandom.h
+++ b/arch/powerpc/include/asm/archrandom.h
@@ -38,12 +38,12 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 #endif /* CONFIG_ARCH_RANDOM */
 
 #ifdef CONFIG_PPC_POWERNV
-int powernv_hwrng_present(void);
-int powernv_get_random_long(unsigned long *v);
-int powernv_get_random_real_mode(unsigned long *v);
+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 powernv_hwrng_present(void) { return 0; }
-static inline int powernv_get_random_real_mode(unsigned long *v) { return 0; }
+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 88a8f6473c4e..799d40c2ab4f 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -176,13 +176,13 @@ EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
 
 int kvmppc_hwrng_present(void)
 {
-	return powernv_hwrng_present();
+	return pnv_hwrng_present();
 }
 EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
 
 long kvmppc_rm_h_random(struct kvm_vcpu *vcpu)
 {
-	if (powernv_get_random_real_mode(&vcpu->arch.regs.gpr[4]))
+	if (pnv_get_random_real_mode(&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 bd5ad5f351c2..386b44660e76 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -21,24 +21,24 @@
 
 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
 
-struct powernv_rng {
+struct pnv_rng {
 	void __iomem *regs;
 	void __iomem *regs_real;
 	unsigned long mask;
 };
 
-static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
+static DEFINE_PER_CPU(struct pnv_rng *, pnv_rng);
 
-int powernv_hwrng_present(void)
+int pnv_hwrng_present(void)
 {
-	struct powernv_rng *rng;
+	struct pnv_rng *rng;
 
-	rng = get_cpu_var(powernv_rng);
+	rng = get_cpu_var(pnv_rng);
 	put_cpu_var(rng);
 	return rng != NULL;
 }
 
-static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
+static unsigned long rng_whiten(struct pnv_rng *rng, unsigned long val)
 {
 	unsigned long parity;
 
@@ -58,18 +58,18 @@ static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
 	return val;
 }
 
-int powernv_get_random_real_mode(unsigned long *v)
+int pnv_get_random_real_mode(unsigned long *v)
 {
-	struct powernv_rng *rng;
+	struct pnv_rng *rng;
 
-	rng = raw_cpu_read(powernv_rng);
+	rng = raw_cpu_read(pnv_rng);
 
 	*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
 
 	return 1;
 }
 
-static int powernv_get_random_darn(unsigned long *v)
+static int pnv_get_random_darn(unsigned long *v)
 {
 	unsigned long val;
 
@@ -93,19 +93,19 @@ static int __init initialise_darn(void)
 		return -ENODEV;
 
 	for (i = 0; i < 10; i++) {
-		if (powernv_get_random_darn(&val)) {
-			ppc_md.get_random_seed = powernv_get_random_darn;
+		if (pnv_get_random_darn(&val)) {
+			ppc_md.get_random_seed = pnv_get_random_darn;
 			return 0;
 		}
 	}
 	return -EIO;
 }
 
-int powernv_get_random_long(unsigned long *v)
+int pnv_get_random_long(unsigned long *v)
 {
-	struct powernv_rng *rng;
+	struct pnv_rng *rng;
 
-	rng = get_cpu_var(powernv_rng);
+	rng = get_cpu_var(pnv_rng);
 
 	*v = rng_whiten(rng, in_be64(rng->regs));
 
@@ -113,9 +113,9 @@ int powernv_get_random_long(unsigned long *v)
 
 	return 1;
 }
-EXPORT_SYMBOL_GPL(powernv_get_random_long);
+EXPORT_SYMBOL_GPL(pnv_get_random_long);
 
-static __init void rng_init_per_cpu(struct powernv_rng *rng,
+static __init void rng_init_per_cpu(struct pnv_rng *rng,
 				    struct device_node *dn)
 {
 	int chip_id, cpu;
@@ -125,16 +125,16 @@ static __init void rng_init_per_cpu(struct powernv_rng *rng,
 		pr_warn("No ibm,chip-id found for %pOF.\n", dn);
 
 	for_each_possible_cpu(cpu) {
-		if (per_cpu(powernv_rng, cpu) == NULL ||
+		if (per_cpu(pnv_rng, cpu) == NULL ||
 		    cpu_to_chip_id(cpu) == chip_id) {
-			per_cpu(powernv_rng, cpu) = rng;
+			per_cpu(pnv_rng, cpu) = rng;
 		}
 	}
 }
 
 static __init int rng_create(struct device_node *dn)
 {
-	struct powernv_rng *rng;
+	struct pnv_rng *rng;
 	struct resource res;
 	unsigned long val;
 
@@ -160,7 +160,7 @@ static __init int rng_create(struct device_node *dn)
 
 	rng_init_per_cpu(rng, dn);
 
-	ppc_md.get_random_seed = powernv_get_random_long;
+	ppc_md.get_random_seed = pnv_get_random_long;
 
 	return 0;
 }
@@ -207,7 +207,7 @@ static int __init pnv_rng_late_init(void)
 	/* In case it wasn't called during init for some other reason. */
 	if (ppc_md.get_random_seed == pnv_get_random_long_early)
 		pnv_get_random_long_early(&v);
-	if (ppc_md.get_random_seed == powernv_get_random_long) {
+	if (ppc_md.get_random_seed == pnv_get_random_long) {
 		for_each_compatible_node(dn, NULL, "ibm,power-rng")
 			of_platform_device_create(dn, NULL, NULL);
 	}
diff --git a/drivers/char/hw_random/powernv-rng.c b/drivers/char/hw_random/powernv-rng.c
index 8da1d7917bdc..429e956f34e1 100644
--- a/drivers/char/hw_random/powernv-rng.c
+++ b/drivers/char/hw_random/powernv-rng.c
@@ -23,7 +23,7 @@ static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait
 	buf = (unsigned long *)data;
 
 	for (i = 0; i < len; i++)
-		powernv_get_random_long(buf++);
+		pnv_get_random_long(buf++);
 
 	return len * sizeof(unsigned long);
 }
-- 
2.35.1

[PATCH v4 2/2] powerpc/kvm: don't crash on missing rng, and use darn

[Jason A. Donenfeld]

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>
---
 arch/powerpc/include/asm/archrandom.h |  5 ----
 arch/powerpc/kvm/book3s_hv_builtin.c  |  7 +++---
 arch/powerpc/platforms/powernv/rng.c  | 34 +++++++--------------------
 3 files changed, 12 insertions(+), 34 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..3abaef5f9ac2 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -19,7 +19,7 @@
 #include <asm/interrupt.h>
 #include <asm/kvm_ppc.h>
 #include <asm/kvm_book3s.h>
-#include <asm/archrandom.h>
+#include <asm/machdep.h>
 #include <asm/xics.h>
 #include <asm/xive.h>
 #include <asm/dbell.h>
@@ -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 386b44660e76..985e200183eb 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;
@@ -105,12 +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 = get_cpu_var(pnv_rng);
+		*v = rng_whiten(rng, in_be64(rng->regs));
+		put_cpu_var(rng);
+	} else {
+		rng = raw_cpu_read(pnv_rng);
+		*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));
+	}
 	return 1;
 }
 EXPORT_SYMBOL_GPL(pnv_get_random_long);
-- 
2.35.1

Re: [PATCH v4 0/2] powerpc rng cleanups

[Sachin Sant]

> On 01-Jul-2022, at 2:19 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> 
> These are two small cleanups for -next.
> 
> This is meant to be atop
> https://lore.kernel.org/all/20220630121654.1939181-1-Jason@zx2c4.com/
> which is expected to land first.
> 
> v4 fixes up an inversion of thr DR flag.
> 
> Jason A. Donenfeld (2):
>  powerpc/powernv: rename remaining rng powernv_ functions to pnv_
>  powerpc/kvm: don't crash on missing rng, and use darn
> 

Boot tested this series and can successfully boot a Power8 server.

fwiw Tested-by: Sachin Sant <sachinp@linux.ibm.com>

- Sachin

Re: [PATCH v4 0/2] powerpc rng cleanups

[Jason A. Donenfeld]

On Sat, Jul 02, 2022 at 04:00:03PM +0530, Sachin Sant wrote:
> > On 01-Jul-2022, at 2:19 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> > 
> > These are two small cleanups for -next.
> > 
> > This is meant to be atop
> > https://lore.kernel.org/all/20220630121654.1939181-1-Jason@zx2c4.com/
> > which is expected to land first.
> > 
> > v4 fixes up an inversion of thr DR flag.
> > 
> > Jason A. Donenfeld (2):
> >  powerpc/powernv: rename remaining rng powernv_ functions to pnv_
> >  powerpc/kvm: don't crash on missing rng, and use darn
> > 
> 
> Boot tested this series and can successfully boot a Power8 server.
> 
> fwiw Tested-by: Sachin Sant <sachinp@linux.ibm.com>

Oh good. 4th time's a charm then. I had assumed this would be for 5.20,
but maybe it'll hit 5.19-rcx instead.

Jason