/**
* kvm_mips_build_ret_to_guest() - Assemble code to return to the guest.
* @addr: Address to start writing code.
*
* Assemble the code to handle return from the guest exit handler
* (kvm_mips_handle_exit()) back to the guest.
*
* Returns: Next address after end of written function.
*/
static void *kvm_mips_build_ret_to_guest(void *addr)
{
u32 *p = addr;
/* Put the saved pointer to vcpu (s1) back into the scratch register */
UASM_i_MTC0(&p, S1, scratch_vcpu[0], scratch_vcpu[1]);
/* Load up the Guest EBASE to minimize the window where BEV is set */
UASM_i_LW(&p, T0, offsetof(struct kvm_vcpu_arch, guest_ebase), K1);
/* Switch EBASE back to the one used by KVM */
uasm_i_mfc0(&p, V1, C0_STATUS);
uasm_i_lui(&p, AT, ST0_BEV >> 16);
uasm_i_or(&p, K0, V1, AT);
uasm_i_mtc0(&p, K0, C0_STATUS);
uasm_i_ehb(&p);
build_set_exc_base(&p, T0);
/* Setup status register for running guest in UM */
uasm_i_ori(&p, V1, V1, ST0_EXL | KSU_USER | ST0_IE);
UASM_i_LA(&p, AT, ~(ST0_CU0 | ST0_MX));
uasm_i_and(&p, V1, V1, AT);
uasm_i_mtc0(&p, V1, C0_STATUS);
uasm_i_ehb(&p);
p = kvm_mips_build_enter_guest(p);
return p;
}
static void __init cps_gen_set_top_bit(u32 **pp, struct uasm_label **pl,
struct uasm_reloc **pr,
unsigned r_addr, int lbl)
{
uasm_i_lui(pp, t0, uasm_rel_hi(0x80000000));
uasm_build_label(pl, *pp, lbl);
uasm_i_ll(pp, t1, 0, r_addr);
uasm_i_or(pp, t1, t1, t0);
uasm_i_sc(pp, t1, 0, r_addr);
uasm_il_beqz(pp, pr, t1, lbl);
uasm_i_nop(pp);
}
/**
* kvm_mips_build_exit() - Assemble common guest exit handler.
* @addr: Address to start writing code.
*
* Assemble the generic guest exit handling code. This is called by the
* exception vectors (generated by kvm_mips_build_exception()), and calls
* kvm_mips_handle_exit(), then either resumes the guest or returns to the host
* depending on the return value.
*
* Returns: Next address after end of written function.
*/
void *kvm_mips_build_exit(void *addr)
{
u32 *p = addr;
unsigned int i;
struct uasm_label labels[3];
struct uasm_reloc relocs[3];
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
/*
* Generic Guest exception handler. We end up here when the guest
* does something that causes a trap to kernel mode.
*
* Both k0/k1 registers will have already been saved (k0 into the vcpu
* structure, and k1 into the scratch_tmp register).
*
* The k1 register will already contain the kvm_vcpu_arch pointer.
*/
/* Start saving Guest context to VCPU */
for (i = 0; i < 32; ++i) {
/* Guest k0/k1 saved later */
if (i == K0 || i == K1)
continue;
UASM_i_SW(&p, i, offsetof(struct kvm_vcpu_arch, gprs[i]), K1);
}
#ifndef CONFIG_CPU_MIPSR6
/* We need to save hi/lo and restore them on the way out */
uasm_i_mfhi(&p, T0);
UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, hi), K1);
uasm_i_mflo(&p, T0);
UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, lo), K1);
#endif
/* Finally save guest k1 to VCPU */
uasm_i_ehb(&p);
UASM_i_MFC0(&p, T0, scratch_tmp[0], scratch_tmp[1]);
UASM_i_SW(&p, T0, offsetof(struct kvm_vcpu_arch, gprs[K1]), K1);
/* Now that context has been saved, we can use other registers */
/* Restore vcpu */
UASM_i_MFC0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);
uasm_i_move(&p, S1, A1);
/* Restore run (vcpu->run) */
UASM_i_LW(&p, A0, offsetof(struct kvm_vcpu, run), A1);
/* Save pointer to run in s0, will be saved by the compiler */
uasm_i_move(&p, S0, A0);
/*
* Save Host level EPC, BadVaddr and Cause to VCPU, useful to process
* the exception
*/
UASM_i_MFC0(&p, K0, C0_EPC);
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, pc), K1);
UASM_i_MFC0(&p, K0, C0_BADVADDR);
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, host_cp0_badvaddr),
K1);
uasm_i_mfc0(&p, K0, C0_CAUSE);
uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch, host_cp0_cause), K1);
/* Now restore the host state just enough to run the handlers */
/* Switch EBASE to the one used by Linux */
/* load up the host EBASE */
uasm_i_mfc0(&p, V0, C0_STATUS);
uasm_i_lui(&p, AT, ST0_BEV >> 16);
uasm_i_or(&p, K0, V0, AT);
uasm_i_mtc0(&p, K0, C0_STATUS);
uasm_i_ehb(&p);
UASM_i_LA_mostly(&p, K0, (long)&ebase);
UASM_i_LW(&p, K0, uasm_rel_lo((long)&ebase), K0);
build_set_exc_base(&p, K0);
if (raw_cpu_has_fpu) {
/*
* If FPU is enabled, save FCR31 and clear it so that later
* ctc1's don't trigger FPE for pending exceptions.
*/
uasm_i_lui(&p, AT, ST0_CU1 >> 16);
uasm_i_and(&p, V1, V0, AT);
uasm_il_beqz(&p, &r, V1, label_fpu_1);
uasm_i_nop(&p);
uasm_i_cfc1(&p, T0, 31);
uasm_i_sw(&p, T0, offsetof(struct kvm_vcpu_arch, fpu.fcr31),
K1);
uasm_i_ctc1(&p, ZERO, 31);
uasm_l_fpu_1(&l, p);
}
if (cpu_has_msa) {
/*
* If MSA is enabled, save MSACSR and clear it so that later
* instructions don't trigger MSAFPE for pending exceptions.
*/
uasm_i_mfc0(&p, T0, C0_CONFIG5);
uasm_i_ext(&p, T0, T0, 27, 1); /* MIPS_CONF5_MSAEN */
uasm_il_beqz(&p, &r, T0, label_msa_1);
uasm_i_nop(&p);
uasm_i_cfcmsa(&p, T0, MSA_CSR);
uasm_i_sw(&p, T0, offsetof(struct kvm_vcpu_arch, fpu.msacsr),
K1);
uasm_i_ctcmsa(&p, MSA_CSR, ZERO);
uasm_l_msa_1(&l, p);
}
/* Now that the new EBASE has been loaded, unset BEV and KSU_USER */
uasm_i_addiu(&p, AT, ZERO, ~(ST0_EXL | KSU_USER | ST0_IE));
uasm_i_and(&p, V0, V0, AT);
uasm_i_lui(&p, AT, ST0_CU0 >> 16);
uasm_i_or(&p, V0, V0, AT);
uasm_i_mtc0(&p, V0, C0_STATUS);
uasm_i_ehb(&p);
/* Load up host GP */
UASM_i_LW(&p, GP, offsetof(struct kvm_vcpu_arch, host_gp), K1);
/* Need a stack before we can jump to "C" */
UASM_i_LW(&p, SP, offsetof(struct kvm_vcpu_arch, host_stack), K1);
/* Saved host state */
UASM_i_ADDIU(&p, SP, SP, -(int)sizeof(struct pt_regs));
/*
* XXXKYMA do we need to load the host ASID, maybe not because the
* kernel entries are marked GLOBAL, need to verify
*/
/* Restore host scratch registers, as we'll have clobbered them */
kvm_mips_build_restore_scratch(&p, K0, SP);
/* Restore RDHWR access */
UASM_i_LA_mostly(&p, K0, (long)&hwrena);
uasm_i_lw(&p, K0, uasm_rel_lo((long)&hwrena), K0);
uasm_i_mtc0(&p, K0, C0_HWRENA);
/* Jump to handler */
/*
* XXXKYMA: not sure if this is safe, how large is the stack??
* Now jump to the kvm_mips_handle_exit() to see if we can deal
* with this in the kernel
*/
UASM_i_LA(&p, T9, (unsigned long)kvm_mips_handle_exit);
uasm_i_jalr(&p, RA, T9);
UASM_i_ADDIU(&p, SP, SP, -CALLFRAME_SIZ);
uasm_resolve_relocs(relocs, labels);
p = kvm_mips_build_ret_from_exit(p);
return p;
}
/**
* kvm_mips_build_vcpu_run() - Assemble function to start running a guest VCPU.
* @addr: Address to start writing code.
*
* Assemble the start of the vcpu_run function to run a guest VCPU. The function
* conforms to the following prototype:
*
* int vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu);
*
* The exit from the guest and return to the caller is handled by the code
* generated by kvm_mips_build_ret_to_host().
*
* Returns: Next address after end of written function.
*/
void *kvm_mips_build_vcpu_run(void *addr)
{
u32 *p = addr;
unsigned int i;
/*
* A0: run
* A1: vcpu
*/
/* k0/k1 not being used in host kernel context */
UASM_i_ADDIU(&p, K1, SP, -(int)sizeof(struct pt_regs));
for (i = 16; i < 32; ++i) {
if (i == 24)
i = 28;
UASM_i_SW(&p, i, offsetof(struct pt_regs, regs[i]), K1);
}
/* Save host status */
uasm_i_mfc0(&p, V0, C0_STATUS);
UASM_i_SW(&p, V0, offsetof(struct pt_regs, cp0_status), K1);
/* Save scratch registers, will be used to store pointer to vcpu etc */
kvm_mips_build_save_scratch(&p, V1, K1);
/* VCPU scratch register has pointer to vcpu */
UASM_i_MTC0(&p, A1, scratch_vcpu[0], scratch_vcpu[1]);
/* Offset into vcpu->arch */
UASM_i_ADDIU(&p, K1, A1, offsetof(struct kvm_vcpu, arch));
/*
* Save the host stack to VCPU, used for exception processing
* when we exit from the Guest
*/
UASM_i_SW(&p, SP, offsetof(struct kvm_vcpu_arch, host_stack), K1);
/* Save the kernel gp as well */
UASM_i_SW(&p, GP, offsetof(struct kvm_vcpu_arch, host_gp), K1);
/*
* Setup status register for running the guest in UM, interrupts
* are disabled
*/
UASM_i_LA(&p, K0, ST0_EXL | KSU_USER | ST0_BEV | ST0_KX_IF_64);
uasm_i_mtc0(&p, K0, C0_STATUS);
uasm_i_ehb(&p);
/* load up the new EBASE */
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, guest_ebase), K1);
build_set_exc_base(&p, K0);
/*
* Now that the new EBASE has been loaded, unset BEV, set
* interrupt mask as it was but make sure that timer interrupts
* are enabled
*/
uasm_i_addiu(&p, K0, ZERO, ST0_EXL | KSU_USER | ST0_IE | ST0_KX_IF_64);
uasm_i_andi(&p, V0, V0, ST0_IM);
uasm_i_or(&p, K0, K0, V0);
uasm_i_mtc0(&p, K0, C0_STATUS);
uasm_i_ehb(&p);
p = kvm_mips_build_enter_guest(p);
return p;
}
