diff options
Diffstat (limited to 'arch/powerpc/kvm/book3s_64_entry.S')
| -rw-r--r-- | arch/powerpc/kvm/book3s_64_entry.S | 429 |
1 files changed, 429 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_64_entry.S b/arch/powerpc/kvm/book3s_64_entry.S new file mode 100644 index 000000000000..a9ab92abffe8 --- /dev/null +++ b/arch/powerpc/kvm/book3s_64_entry.S @@ -0,0 +1,429 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#include <linux/export.h> +#include <asm/asm-offsets.h> +#include <asm/cache.h> +#include <asm/code-patching-asm.h> +#include <asm/exception-64s.h> +#include <asm/kvm_asm.h> +#include <asm/kvm_book3s_asm.h> +#include <asm/mmu.h> +#include <asm/ppc_asm.h> +#include <asm/ptrace.h> +#include <asm/reg.h> +#include <asm/ultravisor-api.h> + +/* + * These are branched to from interrupt handlers in exception-64s.S which set + * IKVM_REAL or IKVM_VIRT, if HSTATE_IN_GUEST was found to be non-zero. + */ + +/* + * This is a hcall, so register convention is as + * Documentation/arch/powerpc/papr_hcalls.rst. + * + * This may also be a syscall from PR-KVM userspace that is to be + * reflected to the PR guest kernel, so registers may be set up for + * a system call rather than hcall. We don't currently clobber + * anything here, but the 0xc00 handler has already clobbered CTR + * and CR0, so PR-KVM can not support a guest kernel that preserves + * those registers across its system calls. + * + * The state of registers is as kvmppc_interrupt, except CFAR is not + * saved, R13 is not in SCRATCH0, and R10 does not contain the trap. + */ +.global kvmppc_hcall +.balign IFETCH_ALIGN_BYTES +kvmppc_hcall: +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + lbz r10,HSTATE_IN_GUEST(r13) + cmpwi r10,KVM_GUEST_MODE_HV_P9 + beq kvmppc_p9_exit_hcall +#endif + ld r10,PACA_EXGEN+EX_R13(r13) + SET_SCRATCH0(r10) + li r10,0xc00 + /* Now we look like kvmppc_interrupt */ + li r11,PACA_EXGEN + b .Lgot_save_area + +/* + * KVM interrupt entry occurs after GEN_INT_ENTRY runs, and follows that + * call convention: + * + * guest R9-R13, CTR, CFAR, PPR saved in PACA EX_xxx save area + * guest (H)DAR, (H)DSISR are also in the save area for relevant interrupts + * guest R13 also saved in SCRATCH0 + * R13 = PACA + * R11 = (H)SRR0 + * R12 = (H)SRR1 + * R9 = guest CR + * PPR is set to medium + * + * With the addition for KVM: + * R10 = trap vector + */ +.global kvmppc_interrupt +.balign IFETCH_ALIGN_BYTES +kvmppc_interrupt: +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + std r10,HSTATE_SCRATCH0(r13) + lbz r10,HSTATE_IN_GUEST(r13) + cmpwi r10,KVM_GUEST_MODE_HV_P9 + beq kvmppc_p9_exit_interrupt + ld r10,HSTATE_SCRATCH0(r13) +#endif + li r11,PACA_EXGEN + cmpdi r10,0x200 + bgt+ .Lgot_save_area + li r11,PACA_EXMC + beq .Lgot_save_area + li r11,PACA_EXNMI +.Lgot_save_area: + add r11,r11,r13 +BEGIN_FTR_SECTION + ld r12,EX_CFAR(r11) + std r12,HSTATE_CFAR(r13) +END_FTR_SECTION_IFSET(CPU_FTR_CFAR) + ld r12,EX_CTR(r11) + mtctr r12 +BEGIN_FTR_SECTION + ld r12,EX_PPR(r11) + std r12,HSTATE_PPR(r13) +END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) + ld r12,EX_R12(r11) + std r12,HSTATE_SCRATCH0(r13) + sldi r12,r9,32 + or r12,r12,r10 + ld r9,EX_R9(r11) + ld r10,EX_R10(r11) + ld r11,EX_R11(r11) + + /* + * Hcalls and other interrupts come here after normalising register + * contents and save locations: + * + * R12 = (guest CR << 32) | interrupt vector + * R13 = PACA + * guest R12 saved in shadow HSTATE_SCRATCH0 + * guest R13 saved in SPRN_SCRATCH0 + */ + std r9,HSTATE_SCRATCH2(r13) + lbz r9,HSTATE_IN_GUEST(r13) + cmpwi r9,KVM_GUEST_MODE_SKIP + beq- .Lmaybe_skip +.Lno_skip: +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE + cmpwi r9,KVM_GUEST_MODE_GUEST + beq kvmppc_interrupt_pr +#endif + b kvmppc_interrupt_hv +#else + b kvmppc_interrupt_pr +#endif + +/* + * "Skip" interrupts are part of a trick KVM uses a with hash guests to load + * the faulting instruction in guest memory from the hypervisor without + * walking page tables. + * + * When the guest takes a fault that requires the hypervisor to load the + * instruction (e.g., MMIO emulation), KVM is running in real-mode with HV=1 + * and the guest MMU context loaded. It sets KVM_GUEST_MODE_SKIP, and sets + * MSR[DR]=1 while leaving MSR[IR]=0, so it continues to fetch HV instructions + * but loads and stores will access the guest context. This is used to load + * the faulting instruction using the faulting guest effective address. + * + * However the guest context may not be able to translate, or it may cause a + * machine check or other issue, which results in a fault in the host + * (even with KVM-HV). + * + * These faults come here because KVM_GUEST_MODE_SKIP was set, so if they + * are (or are likely) caused by that load, the instruction is skipped by + * just returning with the PC advanced +4, where it is noticed the load did + * not execute and it goes to the slow path which walks the page tables to + * read guest memory. + */ +.Lmaybe_skip: + cmpwi r12,BOOK3S_INTERRUPT_MACHINE_CHECK + beq 1f + cmpwi r12,BOOK3S_INTERRUPT_DATA_STORAGE + beq 1f + cmpwi r12,BOOK3S_INTERRUPT_DATA_SEGMENT + beq 1f +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + /* HSRR interrupts get 2 added to interrupt number */ + cmpwi r12,BOOK3S_INTERRUPT_H_DATA_STORAGE | 0x2 + beq 2f +#endif + b .Lno_skip +1: mfspr r9,SPRN_SRR0 + addi r9,r9,4 + mtspr SPRN_SRR0,r9 + ld r12,HSTATE_SCRATCH0(r13) + ld r9,HSTATE_SCRATCH2(r13) + GET_SCRATCH0(r13) + RFI_TO_KERNEL +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE +2: mfspr r9,SPRN_HSRR0 + addi r9,r9,4 + mtspr SPRN_HSRR0,r9 + ld r12,HSTATE_SCRATCH0(r13) + ld r9,HSTATE_SCRATCH2(r13) + GET_SCRATCH0(r13) + HRFI_TO_KERNEL +#endif + +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + +/* Stack frame offsets for kvmppc_p9_enter_guest */ +#define SFS (144 + STACK_FRAME_MIN_SIZE) +#define STACK_SLOT_NVGPRS (SFS - 144) /* 18 gprs */ + +/* + * void kvmppc_p9_enter_guest(struct vcpu *vcpu); + * + * Enter the guest on a ISAv3.0 or later system. + */ +.balign IFETCH_ALIGN_BYTES +_GLOBAL(kvmppc_p9_enter_guest) +EXPORT_SYMBOL_GPL(kvmppc_p9_enter_guest) + mflr r0 + std r0,PPC_LR_STKOFF(r1) + stdu r1,-SFS(r1) + + std r1,HSTATE_HOST_R1(r13) + + mfcr r4 + stw r4,SFS+8(r1) + + reg = 14 + .rept 18 + std reg,STACK_SLOT_NVGPRS + ((reg - 14) * 8)(r1) + reg = reg + 1 + .endr + + ld r4,VCPU_LR(r3) + mtlr r4 + ld r4,VCPU_CTR(r3) + mtctr r4 + ld r4,VCPU_XER(r3) + mtspr SPRN_XER,r4 + + ld r1,VCPU_CR(r3) + +BEGIN_FTR_SECTION + ld r4,VCPU_CFAR(r3) + mtspr SPRN_CFAR,r4 +END_FTR_SECTION_IFSET(CPU_FTR_CFAR) +BEGIN_FTR_SECTION + ld r4,VCPU_PPR(r3) + mtspr SPRN_PPR,r4 +END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) + + reg = 4 + .rept 28 + ld reg,__VCPU_GPR(reg)(r3) + reg = reg + 1 + .endr + + ld r4,VCPU_KVM(r3) + lbz r4,KVM_SECURE_GUEST(r4) + cmpdi r4,0 + ld r4,VCPU_GPR(R4)(r3) + bne .Lret_to_ultra + + mtcr r1 + + ld r0,VCPU_GPR(R0)(r3) + ld r1,VCPU_GPR(R1)(r3) + ld r2,VCPU_GPR(R2)(r3) + ld r3,VCPU_GPR(R3)(r3) + + HRFI_TO_GUEST + b . + + /* + * Use UV_RETURN ultracall to return control back to the Ultravisor + * after processing an hypercall or interrupt that was forwarded + * (a.k.a. reflected) to the Hypervisor. + * + * All registers have already been reloaded except the ucall requires: + * R0 = hcall result + * R2 = SRR1, so UV can detect a synthesized interrupt (if any) + * R3 = UV_RETURN + */ +.Lret_to_ultra: + mtcr r1 + ld r1,VCPU_GPR(R1)(r3) + + ld r0,VCPU_GPR(R3)(r3) + mfspr r2,SPRN_SRR1 + LOAD_REG_IMMEDIATE(r3, UV_RETURN) + sc 2 + +/* + * kvmppc_p9_exit_hcall and kvmppc_p9_exit_interrupt are branched to from + * above if the interrupt was taken for a guest that was entered via + * kvmppc_p9_enter_guest(). + * + * The exit code recovers the host stack and vcpu pointer, saves all guest GPRs + * and CR, LR, XER as well as guest MSR and NIA into the VCPU, then re- + * establishes the host stack and registers to return from the + * kvmppc_p9_enter_guest() function, which saves CTR and other guest registers + * (SPRs and FP, VEC, etc). + */ +.balign IFETCH_ALIGN_BYTES +kvmppc_p9_exit_hcall: + mfspr r11,SPRN_SRR0 + mfspr r12,SPRN_SRR1 + li r10,0xc00 + std r10,HSTATE_SCRATCH0(r13) + +.balign IFETCH_ALIGN_BYTES +kvmppc_p9_exit_interrupt: + /* + * If set to KVM_GUEST_MODE_HV_P9 but we're still in the + * hypervisor, that means we can't return from the entry stack. + */ + rldicl. r10,r12,64-MSR_HV_LG,63 + bne- kvmppc_p9_bad_interrupt + + std r1,HSTATE_SCRATCH1(r13) + std r3,HSTATE_SCRATCH2(r13) + ld r1,HSTATE_HOST_R1(r13) + ld r3,HSTATE_KVM_VCPU(r13) + + std r9,VCPU_CR(r3) + +1: + std r11,VCPU_PC(r3) + std r12,VCPU_MSR(r3) + + reg = 14 + .rept 18 + std reg,__VCPU_GPR(reg)(r3) + reg = reg + 1 + .endr + + /* r1, r3, r9-r13 are saved to vcpu by C code */ + std r0,VCPU_GPR(R0)(r3) + std r2,VCPU_GPR(R2)(r3) + reg = 4 + .rept 5 + std reg,__VCPU_GPR(reg)(r3) + reg = reg + 1 + .endr + + LOAD_PACA_TOC() + + mflr r4 + std r4,VCPU_LR(r3) + mfspr r4,SPRN_XER + std r4,VCPU_XER(r3) + + reg = 14 + .rept 18 + ld reg,STACK_SLOT_NVGPRS + ((reg - 14) * 8)(r1) + reg = reg + 1 + .endr + + lwz r4,SFS+8(r1) + mtcr r4 + + /* + * Flush the link stack here, before executing the first blr on the + * way out of the guest. + * + * The link stack won't match coming out of the guest anyway so the + * only cost is the flush itself. The call clobbers r0. + */ +1: nop + patch_site 1b patch__call_kvm_flush_link_stack_p9 + + addi r1,r1,SFS + ld r0,PPC_LR_STKOFF(r1) + mtlr r0 + blr + +/* + * Took an interrupt somewhere right before HRFID to guest, so registers are + * in a bad way. Return things hopefully enough to run host virtual code and + * run the Linux interrupt handler (SRESET or MCE) to print something useful. + * + * We could be really clever and save all host registers in known locations + * before setting HSTATE_IN_GUEST, then restoring them all here, and setting + * return address to a fixup that sets them up again. But that's a lot of + * effort for a small bit of code. Lots of other things to do first. + */ +kvmppc_p9_bad_interrupt: +BEGIN_MMU_FTR_SECTION + /* + * Hash host doesn't try to recover MMU (requires host SLB reload) + */ + b . +END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_RADIX) + /* + * Clean up guest registers to give host a chance to run. + */ + li r10,0 + mtspr SPRN_AMR,r10 + mtspr SPRN_IAMR,r10 + mtspr SPRN_CIABR,r10 + mtspr SPRN_DAWRX0,r10 +BEGIN_FTR_SECTION + mtspr SPRN_DAWRX1,r10 +END_FTR_SECTION_IFSET(CPU_FTR_DAWR1) + + /* + * Switch to host MMU mode (don't have the real host PID but we aren't + * going back to userspace). + */ + hwsync + isync + + mtspr SPRN_PID,r10 + + ld r10, HSTATE_KVM_VCPU(r13) + ld r10, VCPU_KVM(r10) + lwz r10, KVM_HOST_LPID(r10) + mtspr SPRN_LPID,r10 + + ld r10, HSTATE_KVM_VCPU(r13) + ld r10, VCPU_KVM(r10) + ld r10, KVM_HOST_LPCR(r10) + mtspr SPRN_LPCR,r10 + + isync + + /* + * Set GUEST_MODE_NONE so the handler won't branch to KVM, and clear + * MSR_RI in r12 ([H]SRR1) so the handler won't try to return. + */ + li r10,KVM_GUEST_MODE_NONE + stb r10,HSTATE_IN_GUEST(r13) + li r10,MSR_RI + andc r12,r12,r10 + + /* + * Go back to interrupt handler. MCE and SRESET have their specific + * PACA save area so they should be used directly. They set up their + * own stack. The other handlers all use EXGEN. They will use the + * guest r1 if it looks like a kernel stack, so just load the + * emergency stack and go to program check for all other interrupts. + */ + ld r10,HSTATE_SCRATCH0(r13) + cmpwi r10,BOOK3S_INTERRUPT_MACHINE_CHECK + beq .Lcall_machine_check_common + + cmpwi r10,BOOK3S_INTERRUPT_SYSTEM_RESET + beq .Lcall_system_reset_common + + b . + +.Lcall_machine_check_common: + b machine_check_common + +.Lcall_system_reset_common: + b system_reset_common +#endif |