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:
- https://github.com/linuxppc/linux/commit/f3eac426657d985b97c92fa5f7ae1d43f04...
- 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