Hi Suzuki, On 9/17/18 12:41 PM, Suzuki K Poulose wrote: > VTCR_EL2 holds the following key stage2 translation table > parameters: > SL0 - Entry level in the page table lookup. > T0SZ - Denotes the size of the memory addressed by the table. > > We have been using fixed values for the SL0 depending on the > page size as we have a fixed IPA size. But since we are about > to make it dynamic, we need to calculate the SL0 at runtime > per VM. This patch adds a helper to compute the value of SL0 > for a VM based on the IPA size. > > Cc: Marc Zyngier <marc.zyngier@xxxxxxx> > Cc: Christoffer Dall <cdall@xxxxxxxxxx> > Cc: Eric Auger <eric.auger@xxxxxxxxxx> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> > --- > Changes since v3: > - Update reference to latest ARM ARM. > - Update per-vm VTCR value of SL0. > - Add helpers to decode levels from SL0. > - Didn't pick up Reviewed-by tag from Eric, as there > are some new changes in this version > --- > arch/arm64/include/asm/kvm_arm.h | 51 +++++++++++++++++++++++++------- > arch/arm64/kvm/reset.c | 1 + > 2 files changed, 41 insertions(+), 11 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h > index 3fb1d440be6e..5c1487dc5dca 100644 > --- a/arch/arm64/include/asm/kvm_arm.h > +++ b/arch/arm64/include/asm/kvm_arm.h > @@ -121,7 +121,6 @@ > #define VTCR_EL2_IRGN0_WBWA TCR_IRGN0_WBWA > #define VTCR_EL2_SL0_SHIFT 6 > #define VTCR_EL2_SL0_MASK (3 << VTCR_EL2_SL0_SHIFT) > -#define VTCR_EL2_SL0_LVL1 (1 << VTCR_EL2_SL0_SHIFT) > #define VTCR_EL2_T0SZ_MASK 0x3f > #define VTCR_EL2_VS_SHIFT 19 > #define VTCR_EL2_VS_8BIT (0 << VTCR_EL2_VS_SHIFT) > @@ -148,29 +147,59 @@ > /* > * Stage2 translation configuration: > * 64kB pages (TG0 = 1) > - * 2 level page tables (SL = 1) > */ > -#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SL0_LVL1) > -#define VTTBR_X_TGRAN_MAGIC 38 > +#define VTCR_EL2_TGRAN VTCR_EL2_TG0_64K > +#define VTCR_EL2_TGRAN_SL0_BASE 3UL the name if not obvious. I understand this is yet another magic number used in the formulae below: SL0(PAGE_SIZE, Entry_level) = SL0_BASE(PAGE_SIZE) - Entry_Level I first tried to map this onto some spec fields. May be worth a comment? Besides Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx> Thanks Eric > + > #elif defined(CONFIG_ARM64_16K_PAGES) > /* > * Stage2 translation configuration: > * 16kB pages (TG0 = 2) > - * 2 level page tables (SL = 1) > */ > -#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_16K | VTCR_EL2_SL0_LVL1) > -#define VTTBR_X_TGRAN_MAGIC 42 > +#define VTCR_EL2_TGRAN VTCR_EL2_TG0_16K > +#define VTCR_EL2_TGRAN_SL0_BASE 3UL > #else /* 4K */ > /* > * Stage2 translation configuration: > * 4kB pages (TG0 = 0) > - * 3 level page tables (SL = 1) > */ > -#define VTCR_EL2_TGRAN_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SL0_LVL1) > -#define VTTBR_X_TGRAN_MAGIC 37 > +#define VTCR_EL2_TGRAN VTCR_EL2_TG0_4K > +#define VTCR_EL2_TGRAN_SL0_BASE 2UL > #endif > > -#define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN_FLAGS) > +#define VTCR_EL2_FLAGS (VTCR_EL2_COMMON_BITS | VTCR_EL2_TGRAN) > +/* > + * VTCR_EL2:SL0 indicates the entry level for Stage2 translation. > + * Interestingly, it depends on the page size. > + * See D.10.2.121, VTCR_EL2, in ARM DDI 0487C.a > + * > + * ----------------------------------------- > + * | Entry level | 4K | 16K/64K | > + * ------------------------------------------ > + * | Level: 0 | 2 | - | > + * ------------------------------------------ > + * | Level: 1 | 1 | 2 | > + * ------------------------------------------ > + * | Level: 2 | 0 | 1 | > + * ------------------------------------------ > + * | Level: 3 | - | 0 | > + * ------------------------------------------ > + * > + * That table roughly translates to : > + * > + * SL0(PAGE_SIZE, Entry_level) = SL0_BASE(PAGE_SIZE) - Entry_Level > + * > + * Where SL0_BASE(4K) = 2 and SL0_BASE(16K) = 3, SL0_BASE(64K) = 3, provided > + * we take care of ruling out the unsupported cases and > + * Entry_Level = 4 - Number_of_levels. > + * > + */ > +#define VTCR_EL2_LVLS_TO_SL0(levels) \ > + ((VTCR_EL2_TGRAN_SL0_BASE - (4 - (levels))) << VTCR_EL2_SL0_SHIFT) > +#define VTCR_EL2_SL0_TO_LVLS(sl0) \ > + ((sl0) + 4 - VTCR_EL2_TGRAN_SL0_BASE) > +#define VTCR_EL2_LVLS(vtcr) \ > + VTCR_EL2_SL0_TO_LVLS(((vtcr) & VTCR_EL2_SL0_MASK) >> VTCR_EL2_SL0_SHIFT) > /* > * ARM VMSAv8-64 defines an algorithm for finding the translation table > * descriptors in section D4.2.8 in ARM DDI 0487C.a. > diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c > index e0c49377b771..d9b7a00993b6 100644 > --- a/arch/arm64/kvm/reset.c > +++ b/arch/arm64/kvm/reset.c > @@ -167,6 +167,7 @@ int kvm_arm_config_vm(struct kvm *kvm, unsigned long type) > vtcr |= (kvm_get_vmid_bits() == 16) ? > VTCR_EL2_VS_16BIT : > VTCR_EL2_VS_8BIT; > + vtcr |= VTCR_EL2_LVLS_TO_SL0(kvm_stage2_levels(kvm)); > kvm->arch.vtcr = vtcr; > return 0; > } >
