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authorJason A. Donenfeld <Jason@zx2c4.com>2022-06-22 12:54:35 +0200
committerJason A. Donenfeld <Jason@zx2c4.com>2022-07-19 19:37:50 +0200
commit850190e5d421544fdf95652be2b4575d45fd4298 (patch)
tree1c26298f7a009e3319b9e7d06e35a237d08fbb50 /arch
parentpowerpc/powernv: rename remaining rng powernv_ functions to pnv_ (diff)
downloadlinux-dev-850190e5d421544fdf95652be2b4575d45fd4298.tar.xz
linux-dev-850190e5d421544fdf95652be2b4575d45fd4298.zip
powerpc/kvm: don't crash on missing rng, and use darn
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 <sachinp@linux.ibm.com> Fixes: e928e9cb3601 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.") Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/include/asm/archrandom.h5
-rw-r--r--arch/powerpc/kvm/book3s_hv_builtin.c7
-rw-r--r--arch/powerpc/platforms/powernv/rng.c34
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);