Hi Joel, On Mon, Aug 18 2014 at 9:36:04 pm BST, Joel Schopp <joel.schopp@xxxxxxx> wrote: > The current VTTBR_BADDR_MASK only masks 39 bits, which is broken on current > systems. Rather than just add a bit it seems like a good time to also set > things at run-time instead of compile time to accomodate more hardware. > > This patch sets TCR_EL2.PS, VTCR_EL2.T0SZ and vttbr_baddr_mask in runtime, > not compile time. > > In ARMv8, EL2 physical address size (TCR_EL2.PS) and stage2 input address > size (VTCR_EL2.T0SZE) cannot be determined in compile time since they > depend on hardware capability. > > According to Table D4-23 and Table D4-25 in ARM DDI 0487A.b document, > vttbr_x is calculated using different fixed values with consideration > of T0SZ, granule size and the level of translation tables. Therefore, > vttbr_baddr_mask should be determined dynamically. > > Changes since v4: > More minor cleanups from review > Moved some functions into headers > > Changes since v3: > Another rebase > Addressed minor comments from v2 > > Changes since v2: > Rebased on https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next branch > > Changes since v1: > Rebased fix on Jungseok Lee's patch https://lkml.org/lkml/2014/5/12/189 to > provide better long term fix. Updated that patch to log error instead of > silently fail on unaligned vttbr. > > Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > Cc: Sungjinn Chung <sungjinn.chung@xxxxxxxxxxx> > Signed-off-by: Jungseok Lee <jays.lee@xxxxxxxxxxx> > Signed-off-by: Joel Schopp <joel.schopp@xxxxxxx> > --- > arch/arm/include/asm/kvm_mmu.h | 12 ++++++ > arch/arm/kvm/arm.c | 17 +++++++- > arch/arm64/include/asm/kvm_arm.h | 17 +------- > arch/arm64/include/asm/kvm_mmu.h | 78 ++++++++++++++++++++++++++++++++++++++ > arch/arm64/kvm/hyp-init.S | 20 +++++++--- > 5 files changed, 122 insertions(+), 22 deletions(-) > > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h > index 5c7aa3c..73f6ff6 100644 > --- a/arch/arm/include/asm/kvm_mmu.h > +++ b/arch/arm/include/asm/kvm_mmu.h > @@ -166,6 +166,18 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva, > > void stage2_flush_vm(struct kvm *kvm); > > +static inline int kvm_get_phys_addr_shift(void) > +{ > + return KVM_PHYS_SHIFT; > +} > + > +static inline int set_vttbr_baddr_mask(void) > +{ > + vttbr_baddr_mask = VTTBR_BADDR_MASK; Have you tried compiling this? Apart from the obvious missing definition of the variable, I'm not fond of functions with side-effects hidden in an include file. What is wrong with just returning the mask and letting the common code setting it? > + return 0; > +} > + > + > #endif /* !__ASSEMBLY__ */ > > #endif /* __ARM_KVM_MMU_H__ */ > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 3c82b37..f396eb7 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -37,6 +37,7 @@ > #include <asm/mman.h> > #include <asm/tlbflush.h> > #include <asm/cacheflush.h> > +#include <asm/cputype.h> > #include <asm/virt.h> > #include <asm/kvm_arm.h> > #include <asm/kvm_asm.h> > @@ -466,8 +467,14 @@ static void update_vttbr(struct kvm *kvm) > /* update vttbr to be used with the new vmid */ > pgd_phys = virt_to_phys(kvm->arch.pgd); > vmid = ((u64)(kvm->arch.vmid) << VTTBR_VMID_SHIFT) & VTTBR_VMID_MASK; > - kvm->arch.vttbr = pgd_phys & VTTBR_BADDR_MASK; > - kvm->arch.vttbr |= vmid; > + > + /* > + * If the VTTBR isn't aligned there is something wrong with the system > + * or kernel. > + */ > + BUG_ON(pgd_phys & ~vttbr_baddr_mask); > + > + kvm->arch.vttbr = pgd_phys | vmid; > > spin_unlock(&kvm_vmid_lock); > } > @@ -1052,6 +1059,12 @@ int kvm_arch_init(void *opaque) > } > } > > + err = set_vttbr_baddr_mask(); > + if (err) { > + kvm_err("Cannot set vttbr_baddr_mask\n"); > + return -EINVAL; > + } > + > cpu_notifier_register_begin(); > > err = init_hyp_mode(); > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h > index 3d69030..8dbef70 100644 > --- a/arch/arm64/include/asm/kvm_arm.h > +++ b/arch/arm64/include/asm/kvm_arm.h > @@ -94,7 +94,6 @@ > /* TCR_EL2 Registers bits */ > #define TCR_EL2_TBI (1 << 20) > #define TCR_EL2_PS (7 << 16) > -#define TCR_EL2_PS_40B (2 << 16) > #define TCR_EL2_TG0 (1 << 14) > #define TCR_EL2_SH0 (3 << 12) > #define TCR_EL2_ORGN0 (3 << 10) > @@ -103,8 +102,6 @@ > #define TCR_EL2_MASK (TCR_EL2_TG0 | TCR_EL2_SH0 | \ > TCR_EL2_ORGN0 | TCR_EL2_IRGN0 | TCR_EL2_T0SZ) > > -#define TCR_EL2_FLAGS (TCR_EL2_PS_40B) > - > /* VTCR_EL2 Registers bits */ > #define VTCR_EL2_PS_MASK (7 << 16) > #define VTCR_EL2_TG0_MASK (1 << 14) > @@ -119,36 +116,28 @@ > #define VTCR_EL2_SL0_MASK (3 << 6) > #define VTCR_EL2_SL0_LVL1 (1 << 6) > #define VTCR_EL2_T0SZ_MASK 0x3f > -#define VTCR_EL2_T0SZ_40B 24 > +#define VTCR_EL2_T0SZ(bits) (64 - (bits)) > > #ifdef CONFIG_ARM64_64K_PAGES > /* > * Stage2 translation configuration: > - * 40bits output (PS = 2) > - * 40bits input (T0SZ = 24) > * 64kB pages (TG0 = 1) > * 2 level page tables (SL = 1) > */ > #define VTCR_EL2_FLAGS (VTCR_EL2_TG0_64K | VTCR_EL2_SH0_INNER | \ > VTCR_EL2_ORGN0_WBWA | VTCR_EL2_IRGN0_WBWA | \ > - VTCR_EL2_SL0_LVL1 | VTCR_EL2_T0SZ_40B) > -#define VTTBR_X (38 - VTCR_EL2_T0SZ_40B) > + VTCR_EL2_SL0_LVL1) > #else > /* > * Stage2 translation configuration: > - * 40bits output (PS = 2) > - * 40bits input (T0SZ = 24) > * 4kB pages (TG0 = 0) > * 3 level page tables (SL = 1) > */ > #define VTCR_EL2_FLAGS (VTCR_EL2_TG0_4K | VTCR_EL2_SH0_INNER | \ > VTCR_EL2_ORGN0_WBWA | VTCR_EL2_IRGN0_WBWA | \ > - VTCR_EL2_SL0_LVL1 | VTCR_EL2_T0SZ_40B) > -#define VTTBR_X (37 - VTCR_EL2_T0SZ_40B) > + VTCR_EL2_SL0_LVL1) > #endif > > -#define VTTBR_BADDR_SHIFT (VTTBR_X - 1) > -#define VTTBR_BADDR_MASK (((1LLU << (40 - VTTBR_X)) - 1) << VTTBR_BADDR_SHIFT) > #define VTTBR_VMID_SHIFT (48LLU) > #define VTTBR_VMID_MASK (0xffLLU << VTTBR_VMID_SHIFT) > > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index 7d29847..b6ae83b 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -152,5 +152,83 @@ static inline void coherent_cache_guest_page(struct kvm_vcpu *vcpu, hva_t hva, > > void stage2_flush_vm(struct kvm *kvm); > > +/* > + * ARMv8 64K architecture limitations: > + * 16 <= T0SZ <= 21 is valid under 3 level of translation tables > + * 18 <= T0SZ <= 34 is valid under 2 level of translation tables > + * 31 <= T0SZ <= 39 is valid under 1 level of transltaion tables > + * > + * ARMv8 4K architecture limitations: > + * 16 <= T0SZ <= 24 is valid under 4 level of translation tables > + * 21 <= T0SZ <= 33 is valid under 3 level of translation tables > + * 30 <= T0SZ <= 39 is valid under 2 level of translation tables > + * > + * For 4K pages we only support 3 or 4 level, giving T0SZ a range of 16 to 33. > + * For 64K pages we only support 2 or 3 level, giving T0SZ a range of 16 to 34. > + * > + * See Table D4-23 and Table D4-25 in ARM DDI 0487A.b to figure out > + * the origin of the hardcoded values, 38 and 37. > + */ > + > +#ifdef CONFIG_ARM64_64K_PAGES > +static inline int t0sz_to_vttbr_x(int t0sz) > +{ > + if (t0sz < 16 || t0sz > 34) { > + kvm_err("Cannot support %d-bit address space\n", 64 - t0sz); > + return 0; 0 is definitely a bad value for something that is an error case. Consider -EINVAL instead. Also, what if we're in a range that only deals with more levels of page tables than the kernel can deal with (remember we use the kernel page table accessors)? See the new ARM64_VA_BITS and ARM64_PGTABLE_LEVELS symbols that are now available, and use them to validate the range you have. > + } > + > + return 38 - t0sz; > +} > +#else /* 4K pages */ > +static inline int t0sz_to_vttbr_x(int t0sz) > +{ > + if (t0sz < 16 || t0sz > 33) { > + kvm_err("Cannot support %d-bit address space\n", 64 - t0sz); > + return 0; Same here. > + } > + return 37 - t0sz; > +} > +#endif > +static inline int kvm_get_phys_addr_shift(void) > +{ > + int pa_range = read_cpuid(ID_AA64MMFR0_EL1) & 0xf; > + > + switch (pa_range) { > + case 0: return 32; > + case 1: return 36; > + case 2: return 40; > + case 3: return 42; > + case 4: return 44; > + case 5: return 48; > + default: > + BUG(); > + return 0; > + } > +} > + > +static u64 vttbr_baddr_mask; Now every compilation unit that includes kvm_mmu.h has an instance of this variable. I doubt that it is the intended effect. > + > +/** > + * set_vttbr_baddr_mask - set mask value for vttbr base address > + * > + * In ARMv8, vttbr_baddr_mask cannot be determined in compile time since the > + * stage2 input address size depends on hardware capability. Thus, we first > + * need to read ID_AA64MMFR0_EL1.PARange and then set vttbr_baddr_mask with > + * consideration of both the granule size and the level of translation tables. > + */ > +static inline int set_vttbr_baddr_mask(void) > +{ > + int t0sz, vttbr_x; > + > + t0sz = VTCR_EL2_T0SZ(kvm_get_phys_addr_shift()); > + vttbr_x = t0sz_to_vttbr_x(t0sz); > + if (!vttbr_x) > + return -EINVAL; > + vttbr_baddr_mask = (((1LLU << (48 - vttbr_x)) - 1) << (vttbr_x - 1)); I think this can now be written as GENMASK_ULL(48, (vttbr_x - 1)). > + return 0; > +} > + > #endif /* __ASSEMBLY__ */ > #endif /* __ARM64_KVM_MMU_H__ */ > diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S > index d968796..c0f7634 100644 > --- a/arch/arm64/kvm/hyp-init.S > +++ b/arch/arm64/kvm/hyp-init.S > @@ -63,17 +63,21 @@ __do_hyp_init: > mrs x4, tcr_el1 > ldr x5, =TCR_EL2_MASK > and x4, x4, x5 > - ldr x5, =TCR_EL2_FLAGS > - orr x4, x4, x5 > - msr tcr_el2, x4 > - > - ldr x4, =VTCR_EL2_FLAGS > /* > * Read the PARange bits from ID_AA64MMFR0_EL1 and set the PS bits in > - * VTCR_EL2. > + * TCR_EL2 and both PS bits and T0SZ bits in VTCR_EL2. > */ > mrs x5, ID_AA64MMFR0_EL1 > bfi x4, x5, #16, #3 > + msr tcr_el2, x4 > + > + ldr x4, =VTCR_EL2_FLAGS > + bfi x4, x5, #16, #3 > + and x5, x5, #0xf > + adr x6, t0sz > + add x6, x6, x5, lsl #2 > + ldr w5, [x6] > + orr x4, x4, x5 You'll need to validate the T0SZ value, and possibly adjust it so that it is compatible with the addressing capability of the kernel. That probably require a slight change of the hyp-init API. > msr vtcr_el2, x4 > > mrs x4, mair_el1 > @@ -109,6 +113,10 @@ target: /* We're now in the trampoline code, switch page tables */ > > /* Hello, World! */ > eret > + > +t0sz: > + .word VTCR_EL2_T0SZ(32), VTCR_EL2_T0SZ(36), VTCR_EL2_T0SZ(40) > + .word VTCR_EL2_T0SZ(42), VTCR_EL2_T0SZ(44), VTCR_EL2_T0SZ(48) > ENDPROC(__kvm_hyp_init) > > .ltorg > Another element that doesn't appear in this patch is that we need a way for the kernel to expose the maximum input address to userspace (and validate that noone puts memory outside of that range). This should be a separate patch, but it is conceptually tied to the same problem. Thanks, M. -- Jazz is not dead. It just smells funny. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
