From: Christoffer Dall <christoffer.d...@linaro.org> Based on the pseudo-code in the ARM ARM, implement a stage 2 software page table walker.
Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org> Signed-off-by: Jintack Lim <jintack....@linaro.org> Signed-off-by: Marc Zyngier <marc.zyng...@arm.com> --- arch/arm64/include/asm/esr.h | 1 + arch/arm64/include/asm/kvm_arm.h | 2 + arch/arm64/include/asm/kvm_nested.h | 13 ++ arch/arm64/kvm/nested.c | 241 ++++++++++++++++++++++++++++ 4 files changed, 257 insertions(+) diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h index f85aa269082c..8efc91435948 100644 --- a/arch/arm64/include/asm/esr.h +++ b/arch/arm64/include/asm/esr.h @@ -136,6 +136,7 @@ #define ESR_ELx_CM (UL(1) << ESR_ELx_CM_SHIFT) /* ISS field definitions for exceptions taken in to Hyp */ +#define ESR_ELx_FSC_ADDRSZ (0x00) #define ESR_ELx_CV (UL(1) << 24) #define ESR_ELx_COND_SHIFT (20) #define ESR_ELx_COND_MASK (UL(0xF) << ESR_ELx_COND_SHIFT) diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h index 55f4525c112c..1e4dbe0b1c8e 100644 --- a/arch/arm64/include/asm/kvm_arm.h +++ b/arch/arm64/include/asm/kvm_arm.h @@ -273,6 +273,8 @@ #define VTTBR_VMID_SHIFT (UL(48)) #define VTTBR_VMID_MASK(size) (_AT(u64, (1 << size) - 1) << VTTBR_VMID_SHIFT) +#define SCTLR_EE (UL(1) << 25) + /* Hyp System Trap Register */ #define HSTR_EL2_T(x) (1 << x) diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h index d4021d0892bd..686ba53379ab 100644 --- a/arch/arm64/include/asm/kvm_nested.h +++ b/arch/arm64/include/asm/kvm_nested.h @@ -17,6 +17,19 @@ extern struct kvm_s2_mmu *lookup_s2_mmu(struct kvm *kvm, u64 vttbr, u64 hcr); extern void kvm_vcpu_load_hw_mmu(struct kvm_vcpu *vcpu); extern void kvm_vcpu_put_hw_mmu(struct kvm_vcpu *vcpu); +struct kvm_s2_trans { + phys_addr_t output; + phys_addr_t block_size; + bool writable; + bool readable; + int level; + u32 esr; + u64 upper_attr; +}; + +extern int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa, + struct kvm_s2_trans *result); + int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe); extern bool forward_traps(struct kvm_vcpu *vcpu, u64 control_bit); extern bool forward_nv_traps(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 4b38dc5c0be3..6a9bd68b769b 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -80,6 +80,247 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu) return ret; } +struct s2_walk_info { + unsigned int pgshift; + unsigned int pgsize; + unsigned int ps; + unsigned int sl; + unsigned int t0sz; +}; + +static unsigned int ps_to_output_size(unsigned int ps) +{ + switch (ps) { + case 0: return 32; + case 1: return 36; + case 2: return 40; + case 3: return 42; + case 4: return 44; + case 5: + default: + return 48; + } +} + +static unsigned int pa_max(void) +{ + /* We always emulate a VM with maximum PA size of KVM_PHYS_SIZE. */ + return KVM_PHYS_SHIFT; +} + +static int esr_s2_fault(struct kvm_vcpu *vcpu, int level, u32 fsc) +{ + u32 esr; + + esr = kvm_vcpu_get_hsr(vcpu) & ~ESR_ELx_FSC; + esr |= fsc; + esr |= level & 0x3; + return esr; +} + +static int check_base_s2_limits(struct kvm_vcpu *vcpu, struct s2_walk_info *wi, + int level, int input_size, int stride) +{ + int start_size; + + /* Check translation limits */ + switch (wi->pgsize) { + case SZ_64K: + if (level == 0 || (level == 1 && pa_max() <= 42)) + return -EFAULT; + break; + case SZ_16K: + if (level == 0 || (level == 1 && pa_max() <= 40)) + return -EFAULT; + break; + case SZ_4K: + if (level < 0 || (level == 0 && pa_max() <= 42)) + return -EFAULT; + break; + } + + /* Check input size limits */ + if (input_size > pa_max() && + (!vcpu_mode_is_32bit(vcpu) || input_size > 40)) + return -EFAULT; + + /* Check number of entries in starting level table */ + start_size = input_size - ((3 - level) * stride + wi->pgshift); + if (start_size < 1 || start_size > stride + 4) + return -EFAULT; + + return 0; +} + +/* Check if output is within boundaries */ +static int check_output_size(struct kvm_vcpu *vcpu, struct s2_walk_info *wi, + phys_addr_t output) +{ + unsigned int output_size = ps_to_output_size(wi->ps); + + if (output_size > pa_max()) + output_size = pa_max(); + + if (output_size != 48 && (output & GENMASK_ULL(47, output_size))) + return -1; + + return 0; +} + +/* + * This is essentially a C-version of the pseudo code from the ARM ARM + * AArch64.TranslationTableWalk function. I strongly recommend looking at + * that pseudocode in trying to understand this. + * + * Must be called with the kvm->srcy read lock held + */ +static int walk_nested_s2_pgd(struct kvm_vcpu *vcpu, phys_addr_t ipa, + struct s2_walk_info *wi, struct kvm_s2_trans *out) +{ + u64 vttbr = vcpu_read_sys_reg(vcpu, VTTBR_EL2); + int first_block_level, level, stride, input_size, base_lower_bound; + phys_addr_t base_addr; + unsigned int addr_top, addr_bottom; + u64 desc; /* page table entry */ + int ret; + phys_addr_t paddr; + + switch (wi->pgsize) { + case SZ_64K: + case SZ_16K: + level = 3 - wi->sl; + first_block_level = 2; + break; + case SZ_4K: + level = 2 - wi->sl; + first_block_level = 1; + break; + default: + /* GCC is braindead */ + WARN(1, "Page size is none of 4K, 16K or 64K"); + } + + stride = wi->pgshift - 3; + input_size = 64 - wi->t0sz; + if (input_size > 48 || input_size < 25) + return -EFAULT; + + ret = check_base_s2_limits(vcpu, wi, level, input_size, stride); + if (WARN_ON(ret)) + return ret; + + if (check_output_size(vcpu, wi, vttbr)) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_ADDRSZ); + return 1; + } + + base_lower_bound = 3 + input_size - ((3 - level) * stride + + wi->pgshift); + base_addr = vttbr & GENMASK_ULL(47, base_lower_bound); + + addr_top = input_size - 1; + + while (1) { + phys_addr_t index; + + addr_bottom = (3 - level) * stride + wi->pgshift; + index = (ipa & GENMASK_ULL(addr_top, addr_bottom)) + >> (addr_bottom - 3); + + paddr = base_addr | index; + ret = kvm_read_guest(vcpu->kvm, paddr, &desc, sizeof(desc)); + if (ret < 0) + return ret; + + /* + * Handle reversedescriptors if endianness differs between the + * host and the guest hypervisor. + */ + if (vcpu_read_sys_reg(vcpu, SCTLR_EL2) & SCTLR_EE) + desc = be64_to_cpu(desc); + else + desc = le64_to_cpu(desc); + + /* Check for valid descriptor at this point */ + if (!(desc & 1) || ((desc & 3) == 1 && level == 3)) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_FAULT); + return 1; + } + + /* We're at the final level or block translation level */ + if ((desc & 3) == 1 || level == 3) + break; + + if (check_output_size(vcpu, wi, desc)) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_ADDRSZ); + return 1; + } + + base_addr = desc & GENMASK_ULL(47, wi->pgshift); + + level += 1; + addr_top = addr_bottom - 1; + } + + if (level < first_block_level) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_FAULT); + return 1; + } + + /* + * We don't use the contiguous bit in the stage-2 ptes, so skip check + * for misprogramming of the contiguous bit. + */ + + if (check_output_size(vcpu, wi, desc)) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_ADDRSZ); + return 1; + } + + if (!(desc & BIT(10))) { + out->esr = esr_s2_fault(vcpu, level, ESR_ELx_FSC_ACCESS); + return 1; + } + + /* Calculate and return the result */ + paddr = (desc & GENMASK_ULL(47, addr_bottom)) | + (ipa & GENMASK_ULL(addr_bottom - 1, 0)); + out->output = paddr; + out->block_size = 1UL << ((3 - level) * stride + wi->pgshift); + out->readable = desc & (0b01 << 6); + out->writable = desc & (0b10 << 6); + out->level = level; + out->upper_attr = desc & GENMASK_ULL(63, 52); + return 0; +} + +int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa, + struct kvm_s2_trans *result) +{ + u64 vtcr = vcpu_read_sys_reg(vcpu, VTCR_EL2); + struct s2_walk_info wi; + + if (!nested_virt_in_use(vcpu)) + return 0; + + wi.t0sz = vtcr & TCR_EL2_T0SZ_MASK; + + switch (vtcr & VTCR_EL2_TG0_MASK) { + case VTCR_EL2_TG0_4K: + wi.pgshift = 12; break; + case VTCR_EL2_TG0_16K: + wi.pgshift = 14; break; + case VTCR_EL2_TG0_64K: + default: + wi.pgshift = 16; break; + } + wi.pgsize = 1UL << wi.pgshift; + wi.ps = (vtcr & VTCR_EL2_PS_MASK) >> VTCR_EL2_PS_SHIFT; + wi.sl = (vtcr & VTCR_EL2_SL0_MASK) >> VTCR_EL2_SL0_SHIFT; + + return walk_nested_s2_pgd(vcpu, gipa, &wi, result); +} + /* Must be called with kvm->lock held */ struct kvm_s2_mmu *lookup_s2_mmu(struct kvm *kvm, u64 vttbr, u64 hcr) { -- 2.20.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm