[PATCH v5 0/2] powerpc rng cleanups

STALE1502d

Revision v5 of 4 in this series.

7 messages, 2 authors, 2022-07-27 · open the first message on its own page

[PATCH v5 0/2] powerpc rng cleanups

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-11 23:24:59

These are two small cleanups for -next. This v5 rebases on the latest
git master, as some whitespace was added that made v4 no longer apply.

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 v5 1/2] powerpc/powernv: rename remaining rng powernv_ functions to pnv_

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-11 23:25:02

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>
Tested-by: Sachin Sant <redacted>
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 3805ad13b8f3..b5cd82eab9b3 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;
 }

@@ -208,7 +208,7 @@ static int __init pnv_rng_late_init(void)
 	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 v5 2/2] powerpc/kvm: don't crash on missing rng, and use darn

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-11 23:25:07

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>
Tested-by: Sachin Sant <redacted>
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 b5cd82eab9b3..196aa70fe043 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 v5 0/2] powerpc rng cleanups

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-18 13:09:33

Hey again,

On Tue, Jul 12, 2022 at 01:24:46AM +0200, Jason A. Donenfeld wrote:

These are two small cleanups for -next. This v5 rebases on the latest
git master, as some whitespace was added that made v4 no longer apply.

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(-)

I think v5 has reached a completion point. Could you queue these up in
some PPC tree for 5.20?

Thanks,
Jason

Re: [PATCH v5 0/2] powerpc rng cleanups

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-27 01:37:18

Hi Michael,

On Mon, Jul 18, 2022 at 3:09 PM Jason A. Donenfeld [off-list ref] wrote:

Hey again,

On Tue, Jul 12, 2022 at 01:24:46AM +0200, Jason A. Donenfeld wrote:

quoted

These are two small cleanups for -next. This v5 rebases on the latest
git master, as some whitespace was added that made v4 no longer apply.

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(-)

I think v5 has reached a completion point. Could you queue these up in
some PPC tree for 5.20?

Just paging again. Do you think you could queue these up for 5.20?
This trivial series is over a month old now.

Thanks,
Jason

Re: [PATCH v5 0/2] powerpc rng cleanups

From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2022-07-27 03:54:23

"Jason A. Donenfeld" [off-list ref] writes:

On Mon, Jul 18, 2022 at 3:09 PM Jason A. Donenfeld [off-list ref] wrote:

quoted

On Tue, Jul 12, 2022 at 01:24:46AM +0200, Jason A. Donenfeld wrote:

quoted

These are two small cleanups for -next. This v5 rebases on the latest
git master, as some whitespace was added that made v4 no longer apply.

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(-)

I think v5 has reached a completion point. Could you queue these up in
some PPC tree for 5.20?

Just paging again. Do you think you could queue these up for 5.20?
This trivial series is over a month old now.

It can't claim to fix a guest-triggerable hypervisor crash and also be
"trivial" :)

But yes I plan to queue it for v5.20.

cheers

Re: [PATCH v5 0/2] powerpc rng cleanups

From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: 2022-07-27 11:53:06

Hi Michael,

On Wed, Jul 27, 2022 at 01:54:07PM +1000, Michael Ellerman wrote:

"Jason A. Donenfeld" [off-list ref] writes:

quoted

On Mon, Jul 18, 2022 at 3:09 PM Jason A. Donenfeld [off-list ref] wrote:

quoted

On Tue, Jul 12, 2022 at 01:24:46AM +0200, Jason A. Donenfeld wrote:

quoted

These are two small cleanups for -next. This v5 rebases on the latest
git master, as some whitespace was added that made v4 no longer apply.

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(-)

I think v5 has reached a completion point. Could you queue these up in
some PPC tree for 5.20?

Just paging again. Do you think you could queue these up for 5.20?
This trivial series is over a month old now.

It can't claim to fix a guest-triggerable hypervisor crash and also be
"trivial" :)

:)

But yes I plan to queue it for v5.20.

Okay great. Would be nice to see this in -next sooner rather than later.

Jason

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