Paul Mackerras <paulus@xxxxxxxxx> writes: > The B (segment size) field in the RB operand for the tlbie > instruction is two bits, which we get from the top two bits of > the first doubleword of the HPT entry to be invalidated. These > bits go in bits 8 and 9 of the RB operand (bits 54 and 55 in IBM > bit numbering). > > The compute_tlbie_rb() function gets these bits as v >> (62 - 8), > which is not correct as it will bring in the top 10 bits, not > just the top two. These extra bits could corrupt the AP, AVAL > and L fields in the RB value. To fix this we shift right 62 bits > and then shift left 8 bits, so we only get the two bits of the > B field. Good catch. > > The first doubleword of the HPT entry is under the control of the > guest kernel. In fact, Linux guests will always put zeroes in bits > 54 -- 61 (IBM bits 2 -- 9), but we should not rely on guests doing > this. > > Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > --- > arch/powerpc/include/asm/kvm_book3s_64.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h > index 0aa8179..a37f1a4 100644 > --- a/arch/powerpc/include/asm/kvm_book3s_64.h > +++ b/arch/powerpc/include/asm/kvm_book3s_64.h > @@ -148,7 +148,7 @@ static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r, > /* This covers 14..54 bits of va*/ > rb = (v & ~0x7fUL) << 16; /* AVA field */ > > - rb |= v >> (62 - 8); /* B field */ > + rb |= (v >> HPTE_V_SSIZE_SHIFT) << 8; /* B field */ > /* > * AVA in v had cleared lower 23 bits. We need to derive > * that from pteg index > -- > 2.1.1 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
