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kernel/arch/mips/kvm/entry.c

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Generation of main entry point for the guest, exception handling.
*
* Copyright (C) 2012 MIPS Technologies, Inc.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*
* Copyright (C) 2016 Imagination Technologies Ltd.
*/
#include <linux/kvm_host.h>
#include <linux/log2.h>
#include <asm/mmu_context.h>
#include <asm/msa.h>
#include <asm/setup.h>
#include <asm/tlbex.h>
#include <asm/uasm.h>
/* Register names */
#define ZERO 0
#define AT 1
#define V0 2
#define V1 3
#define A0 4
#define A1 5
#if _MIPS_SIM == _MIPS_SIM_ABI32
#define T0 8
#define T1 9
#define T2 10
#define T3 11
#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
#if _MIPS_SIM == _MIPS_SIM_ABI64 || _MIPS_SIM == _MIPS_SIM_NABI32
#define T0 12
#define T1 13
#define T2 14
#define T3 15
#endif /* _MIPS_SIM == _MIPS_SIM_ABI64 || _MIPS_SIM == _MIPS_SIM_NABI32 */
#define S0 16
#define S1 17
#define T9 25
#define K0 26
#define K1 27
#define GP 28
#define SP 29
#define RA 31
/* Some CP0 registers */
#define C0_PWBASE 5, 5
#define C0_HWRENA 7, 0
#define C0_BADVADDR 8, 0
#define C0_BADINSTR 8, 1
#define C0_BADINSTRP 8, 2
#define C0_PGD 9, 7
#define C0_ENTRYHI 10, 0
#define C0_GUESTCTL1 10, 4
#define C0_STATUS 12, 0
#define C0_GUESTCTL0 12, 6
#define C0_CAUSE 13, 0
#define C0_EPC 14, 0
#define C0_EBASE 15, 1
#define C0_CONFIG5 16, 5
#define C0_DDATA_LO 28, 3
#define C0_ERROREPC 30, 0
#define CALLFRAME_SIZ 32
#ifdef CONFIG_64BIT
#define ST0_KX_IF_64 ST0_KX
#else
#define ST0_KX_IF_64 0
#endif
static unsigned int scratch_vcpu[2] = { C0_DDATA_LO };
static unsigned int scratch_tmp[2] = { C0_ERROREPC };
enum label_id {
label_fpu_1 = 1,
label_msa_1,
label_return_to_host,
label_kernel_asid,
label_exit_common,
};
UASM_L_LA(_fpu_1)
UASM_L_LA(_msa_1)
UASM_L_LA(_return_to_host)
UASM_L_LA(_kernel_asid)
UASM_L_LA(_exit_common)
static void *kvm_mips_build_enter_guest(void *addr);
static void *kvm_mips_build_ret_from_exit(void *addr);
static void *kvm_mips_build_ret_to_guest(void *addr);
static void *kvm_mips_build_ret_to_host(void *addr);
/*
* The version of this function in tlbex.c uses current_cpu_type(), but for KVM
* we assume symmetry.
*/
static int c0_kscratch(void)
{
switch (boot_cpu_type()) {
case CPU_XLP:
case CPU_XLR:
return 22;
default:
return 31;
}
}
/**
* kvm_mips_entry_setup() - Perform global setup for entry code.
*
* Perform global setup for entry code, such as choosing a scratch register.
*
* Returns: 0 on success.
* -errno on failure.
*/
int kvm_mips_entry_setup(void)
{
/*
* We prefer to use KScratchN registers if they are available over the
* defaults above, which may not work on all cores.
*/
unsigned int kscratch_mask = cpu_data[0].kscratch_mask;
if (pgd_reg != -1)
kscratch_mask &= ~BIT(pgd_reg);
/* Pick a scratch register for storing VCPU */
if (kscratch_mask) {
scratch_vcpu[0] = c0_kscratch();
scratch_vcpu[1] = ffs(kscratch_mask) - 1;
kscratch_mask &= ~BIT(scratch_vcpu[1]);
}
/* Pick a scratch register to use as a temp for saving state */
if (kscratch_mask) {
scratch_tmp[0] = c0_kscratch();
scratch_tmp[1] = ffs(kscratch_mask) - 1;
kscratch_mask &= ~BIT(scratch_tmp[1]);
}
return 0;
}
static void kvm_mips_build_save_scratch(u32 **p, unsigned int tmp,
unsigned int frame)
{
/* Save the VCPU scratch register value in cp0_epc of the stack frame */
UASM_i_MFC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);
UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
/* Save the temp scratch register value in cp0_cause of stack frame */
if (scratch_tmp[0] == c0_kscratch()) {
UASM_i_MFC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
UASM_i_SW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
}
}
static void kvm_mips_build_restore_scratch(u32 **p, unsigned int tmp,
unsigned int frame)
{
/*
* Restore host scratch register values saved by
* kvm_mips_build_save_scratch().
*/
UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_epc), frame);
UASM_i_MTC0(p, tmp, scratch_vcpu[0], scratch_vcpu[1]);
if (scratch_tmp[0] == c0_kscratch()) {
UASM_i_LW(p, tmp, offsetof(struct pt_regs, cp0_cause), frame);
UASM_i_MTC0(p, tmp, scratch_tmp[0], scratch_tmp[1]);
}
}
/**
* build_set_exc_base() - Assemble code to write exception base address.
* @p: Code buffer pointer.
* @reg: Source register (generated code may set WG bit in @reg).
*
* Assemble code to modify the exception base address in the EBase register,
* using the appropriately sized access and setting the WG bit if necessary.
*/
static inline void build_set_exc_base(u32 **p, unsigned int reg)
{
if (cpu_has_ebase_wg) {
/* Set WG so that all the bits get written */
uasm_i_ori(p, reg, reg, MIPS_EBASE_WG);
UASM_i_MTC0(p, reg, C0_EBASE);
} else {
uasm_i_mtc0(p, reg, C0_EBASE);
}
}
/**
* 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_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: 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, A0, scratch_vcpu[0], scratch_vcpu[1]);
/* Offset into vcpu->arch */
UASM_i_ADDIU(&p, K1, A0, 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;
}
/**
* kvm_mips_build_enter_guest() - Assemble code to resume guest execution.
* @addr: Address to start writing code.
*
* Assemble the code to resume guest execution. This code is common between the
* initial entry into the guest from the host, and returning from the exit
* handler back to the guest.
*
* Returns: Next address after end of written function.
*/
static void *kvm_mips_build_enter_guest(void *addr)
{
u32 *p = addr;
unsigned int i;
struct uasm_label labels[2];
struct uasm_reloc relocs[2];
struct uasm_label __maybe_unused *l = labels;
struct uasm_reloc __maybe_unused *r = relocs;
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
/* Set Guest EPC */
UASM_i_LW(&p, T0, offsetof(struct kvm_vcpu_arch, pc), K1);
UASM_i_MTC0(&p, T0, C0_EPC);
/* Save normal linux process pgd (VZ guarantees pgd_reg is set) */
if (cpu_has_ldpte)
UASM_i_MFC0(&p, K0, C0_PWBASE);
else
UASM_i_MFC0(&p, K0, c0_kscratch(), pgd_reg);
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, host_pgd), K1);
/*
* Set up KVM GPA pgd.
* This does roughly the same as TLBMISS_HANDLER_SETUP_PGD():
* - call tlbmiss_handler_setup_pgd(mm->pgd)
* - write mm->pgd into CP0_PWBase
*
* We keep S0 pointing at struct kvm so we can load the ASID below.
*/
UASM_i_LW(&p, S0, (int)offsetof(struct kvm_vcpu, kvm) -
(int)offsetof(struct kvm_vcpu, arch), K1);
UASM_i_LW(&p, A0, offsetof(struct kvm, arch.gpa_mm.pgd), S0);
UASM_i_LA(&p, T9, (unsigned long)tlbmiss_handler_setup_pgd);
uasm_i_jalr(&p, RA, T9);
/* delay slot */
if (cpu_has_htw)
UASM_i_MTC0(&p, A0, C0_PWBASE);
else
uasm_i_nop(&p);
/* Set GM bit to setup eret to VZ guest context */
uasm_i_addiu(&p, V1, ZERO, 1);
uasm_i_mfc0(&p, K0, C0_GUESTCTL0);
uasm_i_ins(&p, K0, V1, MIPS_GCTL0_GM_SHIFT, 1);
uasm_i_mtc0(&p, K0, C0_GUESTCTL0);
if (cpu_has_guestid) {
/*
* Set root mode GuestID, so that root TLB refill handler can
* use the correct GuestID in the root TLB.
*/
/* Get current GuestID */
uasm_i_mfc0(&p, T0, C0_GUESTCTL1);
/* Set GuestCtl1.RID = GuestCtl1.ID */
uasm_i_ext(&p, T1, T0, MIPS_GCTL1_ID_SHIFT,
MIPS_GCTL1_ID_WIDTH);
uasm_i_ins(&p, T0, T1, MIPS_GCTL1_RID_SHIFT,
MIPS_GCTL1_RID_WIDTH);
uasm_i_mtc0(&p, T0, C0_GUESTCTL1);
/* GuestID handles dealiasing so we don't need to touch ASID */
goto skip_asid_restore;
}
/* Root ASID Dealias (RAD) */
/* Save host ASID */
UASM_i_MFC0(&p, K0, C0_ENTRYHI);
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, host_entryhi),
K1);
/* Set the root ASID for the Guest */
UASM_i_ADDIU(&p, T1, S0,
offsetof(struct kvm, arch.gpa_mm.context.asid));
/* t1: contains the base of the ASID array, need to get the cpu id */
/* smp_processor_id */
uasm_i_lw(&p, T2, offsetof(struct thread_info, cpu), GP);
/* index the ASID array */
uasm_i_sll(&p, T2, T2, ilog2(sizeof(long)));
UASM_i_ADDU(&p, T3, T1, T2);
UASM_i_LW(&p, K0, 0, T3);
#ifdef CONFIG_MIPS_ASID_BITS_VARIABLE
/*
* reuse ASID array offset
* cpuinfo_mips is a multiple of sizeof(long)
*/
uasm_i_addiu(&p, T3, ZERO, sizeof(struct cpuinfo_mips)/sizeof(long));
uasm_i_mul(&p, T2, T2, T3);
UASM_i_LA_mostly(&p, AT, (long)&cpu_data[0].asid_mask);
UASM_i_ADDU(&p, AT, AT, T2);
UASM_i_LW(&p, T2, uasm_rel_lo((long)&cpu_data[0].asid_mask), AT);
uasm_i_and(&p, K0, K0, T2);
#else
uasm_i_andi(&p, K0, K0, MIPS_ENTRYHI_ASID);
#endif
/* Set up KVM VZ root ASID (!guestid) */
uasm_i_mtc0(&p, K0, C0_ENTRYHI);
skip_asid_restore:
uasm_i_ehb(&p);
/* Disable RDHWR access */
uasm_i_mtc0(&p, ZERO, C0_HWRENA);
/* load the guest context from VCPU and return */
for (i = 1; i < 32; ++i) {
/* Guest k0/k1 loaded later */
if (i == K0 || i == K1)
continue;
UASM_i_LW(&p, i, offsetof(struct kvm_vcpu_arch, gprs[i]), K1);
}
#ifndef CONFIG_CPU_MIPSR6
/* Restore hi/lo */
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, hi), K1);
uasm_i_mthi(&p, K0);
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, lo), K1);
uasm_i_mtlo(&p, K0);
#endif
/* Restore the guest's k0/k1 registers */
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, gprs[K0]), K1);
UASM_i_LW(&p, K1, offsetof(struct kvm_vcpu_arch, gprs[K1]), K1);
/* Jump to guest */
uasm_i_eret(&p);
uasm_resolve_relocs(relocs, labels);
return p;
}
/**
* kvm_mips_build_tlb_refill_exception() - Assemble TLB refill handler.
* @addr: Address to start writing code.
* @handler: Address of common handler (within range of @addr).
*
* Assemble TLB refill exception fast path handler for guest execution.
*
* Returns: Next address after end of written function.
*/
void *kvm_mips_build_tlb_refill_exception(void *addr, void *handler)
{
u32 *p = addr;
struct uasm_label labels[2];
struct uasm_reloc relocs[2];
#ifndef CONFIG_CPU_LOONGSON64
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
#endif
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
/* Save guest k1 into scratch register */
UASM_i_MTC0(&p, K1, scratch_tmp[0], scratch_tmp[1]);
/* Get the VCPU pointer from the VCPU scratch register */
UASM_i_MFC0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);
/* Save guest k0 into VCPU structure */
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu, arch.gprs[K0]), K1);
/*
* Some of the common tlbex code uses current_cpu_type(). For KVM we
* assume symmetry and just disable preemption to silence the warning.
*/
preempt_disable();
#ifdef CONFIG_CPU_LOONGSON64
UASM_i_MFC0(&p, K1, C0_PGD);
uasm_i_lddir(&p, K0, K1, 3); /* global page dir */
#ifndef __PAGETABLE_PMD_FOLDED
uasm_i_lddir(&p, K1, K0, 1); /* middle page dir */
#endif
uasm_i_ldpte(&p, K1, 0); /* even */
uasm_i_ldpte(&p, K1, 1); /* odd */
uasm_i_tlbwr(&p);
#else
/*
* Now for the actual refill bit. A lot of this can be common with the
* Linux TLB refill handler, however we don't need to handle so many
* cases. We only need to handle user mode refills, and user mode runs
* with 32-bit addressing.
*
* Therefore the branch to label_vmalloc generated by build_get_pmde64()
* that isn't resolved should never actually get taken and is harmless
* to leave in place for now.
*/
#ifdef CONFIG_64BIT
build_get_pmde64(&p, &l, &r, K0, K1); /* get pmd in K1 */
#else
build_get_pgde32(&p, K0, K1); /* get pgd in K1 */
#endif
/* we don't support huge pages yet */
build_get_ptep(&p, K0, K1);
build_update_entries(&p, K0, K1);
build_tlb_write_entry(&p, &l, &r, tlb_random);
#endif
preempt_enable();
/* Get the VCPU pointer from the VCPU scratch register again */
UASM_i_MFC0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);
/* Restore the guest's k0/k1 registers */
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu, arch.gprs[K0]), K1);
uasm_i_ehb(&p);
UASM_i_MFC0(&p, K1, scratch_tmp[0], scratch_tmp[1]);
/* Jump to guest */
uasm_i_eret(&p);
return p;
}
/**
* kvm_mips_build_exception() - Assemble first level guest exception handler.
* @addr: Address to start writing code.
* @handler: Address of common handler (within range of @addr).
*
* Assemble exception vector code for guest execution. The generated vector will
* branch to the common exception handler generated by kvm_mips_build_exit().
*
* Returns: Next address after end of written function.
*/
void *kvm_mips_build_exception(void *addr, void *handler)
{
u32 *p = addr;
struct uasm_label labels[2];
struct uasm_reloc relocs[2];
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
/* Save guest k1 into scratch register */
UASM_i_MTC0(&p, K1, scratch_tmp[0], scratch_tmp[1]);
/* Get the VCPU pointer from the VCPU scratch register */
UASM_i_MFC0(&p, K1, scratch_vcpu[0], scratch_vcpu[1]);
UASM_i_ADDIU(&p, K1, K1, offsetof(struct kvm_vcpu, arch));
/* Save guest k0 into VCPU structure */
UASM_i_SW(&p, K0, offsetof(struct kvm_vcpu_arch, gprs[K0]), K1);
/* Branch to the common handler */
uasm_il_b(&p, &r, label_exit_common);
uasm_i_nop(&p);
uasm_l_exit_common(&l, handler);
uasm_resolve_relocs(relocs, labels);
return p;
}
/**
* 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, S0, scratch_vcpu[0], scratch_vcpu[1]);
/*
* 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);
if (cpu_has_badinstr) {
uasm_i_mfc0(&p, K0, C0_BADINSTR);
uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch,
host_cp0_badinstr), K1);
}
if (cpu_has_badinstrp) {
uasm_i_mfc0(&p, K0, C0_BADINSTRP);
uasm_i_sw(&p, K0, offsetof(struct kvm_vcpu_arch,
host_cp0_badinstrp), 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);
}
/* Restore host ASID */
if (!cpu_has_guestid) {
UASM_i_LW(&p, K0, offsetof(struct kvm_vcpu_arch, host_entryhi),
K1);
UASM_i_MTC0(&p, K0, C0_ENTRYHI);
}
/*
* Set up normal Linux process pgd.
* This does roughly the same as TLBMISS_HANDLER_SETUP_PGD():
* - call tlbmiss_handler_setup_pgd(mm->pgd)
* - write mm->pgd into CP0_PWBase
*/
UASM_i_LW(&p, A0,
offsetof(struct kvm_vcpu_arch, host_pgd), K1);
UASM_i_LA(&p, T9, (unsigned long)tlbmiss_handler_setup_pgd);
uasm_i_jalr(&p, RA, T9);
/* delay slot */
if (cpu_has_htw)
UASM_i_MTC0(&p, A0, C0_PWBASE);
else
uasm_i_nop(&p);
/* Clear GM bit so we don't enter guest mode when EXL is cleared */
uasm_i_mfc0(&p, K0, C0_GUESTCTL0);
uasm_i_ins(&p, K0, ZERO, MIPS_GCTL0_GM_SHIFT, 1);
uasm_i_mtc0(&p, K0, C0_GUESTCTL0);
/* Save GuestCtl0 so we can access GExcCode after CPU migration */
uasm_i_sw(&p, K0,
offsetof(struct kvm_vcpu_arch, host_cp0_guestctl0), K1);
if (cpu_has_guestid) {
/*
* Clear root mode GuestID, so that root TLB operations use the
* root GuestID in the root TLB.
*/
uasm_i_mfc0(&p, T0, C0_GUESTCTL1);
/* Set GuestCtl1.RID = MIPS_GCTL1_ROOT_GUESTID (i.e. 0) */
uasm_i_ins(&p, T0, ZERO, MIPS_GCTL1_RID_SHIFT,
MIPS_GCTL1_RID_WIDTH);
uasm_i_mtc0(&p, T0, C0_GUESTCTL1);
}
/* 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);
#ifdef CONFIG_64BIT
uasm_i_ori(&p, V0, V0, ST0_SX | ST0_UX);
#endif
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_move(&p, A0, S0);
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_ret_from_exit() - Assemble guest exit return handler.
* @addr: Address to start writing code.
*
* Assemble the code to handle the return from kvm_mips_handle_exit(), either
* resuming the guest or returning to the host depending on the return value.
*
* Returns: Next address after end of written function.
*/
static void *kvm_mips_build_ret_from_exit(void *addr)
{
u32 *p = addr;
struct uasm_label labels[2];
struct uasm_reloc relocs[2];
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
/* Return from handler Make sure interrupts are disabled */
uasm_i_di(&p, ZERO);
uasm_i_ehb(&p);
/*
* XXXKYMA: k0/k1 could have been blown away if we processed
* an exception while we were handling the exception from the
* guest, reload k1
*/
uasm_i_move(&p, K1, S0);
UASM_i_ADDIU(&p, K1, K1, offsetof(struct kvm_vcpu, arch));
/*
* Check return value, should tell us if we are returning to the
* host (handle I/O etc)or resuming the guest
*/
uasm_i_andi(&p, T0, V0, RESUME_HOST);
uasm_il_bnez(&p, &r, T0, label_return_to_host);
uasm_i_nop(&p);
p = kvm_mips_build_ret_to_guest(p);
uasm_l_return_to_host(&l, p);
p = kvm_mips_build_ret_to_host(p);
uasm_resolve_relocs(relocs, labels);
return p;
}
/**
* 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 (s0) back into the scratch register */
UASM_i_MTC0(&p, S0, 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 | ST0_SX | ST0_UX));
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;
}
/**
* kvm_mips_build_ret_to_host() - Assemble code to return to the host.
* @addr: Address to start writing code.
*
* Assemble the code to handle return from the guest exit handler
* (kvm_mips_handle_exit()) back to the host, i.e. to the caller of the vcpu_run
* function generated by kvm_mips_build_vcpu_run().
*
* Returns: Next address after end of written function.
*/
static void *kvm_mips_build_ret_to_host(void *addr)
{
u32 *p = addr;
unsigned int i;
/* EBASE is already pointing to Linux */
UASM_i_LW(&p, K1, offsetof(struct kvm_vcpu_arch, host_stack), K1);
UASM_i_ADDIU(&p, K1, K1, -(int)sizeof(struct pt_regs));
/*
* r2/v0 is the return code, shift it down by 2 (arithmetic)
* to recover the err code
*/
uasm_i_sra(&p, K0, V0, 2);
uasm_i_move(&p, V0, K0);
/* Load context saved on the host stack */
for (i = 16; i < 31; ++i) {
if (i == 24)
i = 28;
UASM_i_LW(&p, i, offsetof(struct pt_regs, regs[i]), K1);
}
/* 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);
/* Restore RA, which is the address we will return to */
UASM_i_LW(&p, RA, offsetof(struct pt_regs, regs[RA]), K1);
uasm_i_jr(&p, RA);
uasm_i_nop(&p);
return p;
}
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