[PATCH v2 27/29] LoongArch: KVM: Implement vcpu world switch
From: Tianrui Zhao
Date: Mon Feb 20 2023 - 01:59:28 EST
Implement loongarch vcpu world switch, including vcpu enter guest and
vcpu exit from guest, both operations need to save or restore the host
and guest registers.
Signed-off-by: Tianrui Zhao <zhaotianrui@xxxxxxxxxxx>
---
arch/loongarch/kernel/asm-offsets.c | 32 +++
arch/loongarch/kvm/switch.S | 327 ++++++++++++++++++++++++++++
2 files changed, 359 insertions(+)
create mode 100644 arch/loongarch/kvm/switch.S
diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c
index 4bdb203fc..655741c03 100644
--- a/arch/loongarch/kernel/asm-offsets.c
+++ b/arch/loongarch/kernel/asm-offsets.c
@@ -9,6 +9,7 @@
#include <linux/mm.h>
#include <linux/kbuild.h>
#include <linux/suspend.h>
+#include <linux/kvm_host.h>
#include <asm/cpu-info.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
@@ -272,3 +273,34 @@ void output_pbe_defines(void)
BLANK();
}
#endif
+
+void output_kvm_defines(void)
+{
+ COMMENT(" KVM/LOONGARCH Specific offsets. ");
+
+ OFFSET(VCPU_FCSR0, kvm_vcpu_arch, fpu.fcsr);
+ OFFSET(VCPU_FCC, kvm_vcpu_arch, fpu.fcc);
+ BLANK();
+
+ OFFSET(KVM_VCPU_ARCH, kvm_vcpu, arch);
+ OFFSET(KVM_VCPU_KVM, kvm_vcpu, kvm);
+ OFFSET(KVM_VCPU_RUN, kvm_vcpu, run);
+ BLANK();
+
+ OFFSET(KVM_ARCH_HSTACK, kvm_vcpu_arch, host_stack);
+ OFFSET(KVM_ARCH_HGP, kvm_vcpu_arch, host_gp);
+ OFFSET(KVM_ARCH_HANDLE_EXIT, kvm_vcpu_arch, handle_exit);
+ OFFSET(KVM_ARCH_HPGD, kvm_vcpu_arch, host_pgd);
+ OFFSET(KVM_ARCH_GEENTRY, kvm_vcpu_arch, guest_eentry);
+ OFFSET(KVM_ARCH_GPC, kvm_vcpu_arch, pc);
+ OFFSET(KVM_ARCH_GGPR, kvm_vcpu_arch, gprs);
+ OFFSET(KVM_ARCH_HESTAT, kvm_vcpu_arch, host_estat);
+ OFFSET(KVM_ARCH_HBADV, kvm_vcpu_arch, badv);
+ OFFSET(KVM_ARCH_HBADI, kvm_vcpu_arch, badi);
+ OFFSET(KVM_ARCH_HECFG, kvm_vcpu_arch, host_ecfg);
+ OFFSET(KVM_ARCH_HEENTRY, kvm_vcpu_arch, host_eentry);
+ OFFSET(KVM_ARCH_HPERCPU, kvm_vcpu_arch, host_percpu);
+
+ OFFSET(KVM_GPGD, kvm, arch.gpa_mm.pgd);
+ BLANK();
+}
diff --git a/arch/loongarch/kvm/switch.S b/arch/loongarch/kvm/switch.S
new file mode 100644
index 000000000..c0b8062ac
--- /dev/null
+++ b/arch/loongarch/kvm/switch.S
@@ -0,0 +1,327 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/linkage.h>
+#include <asm/stackframe.h>
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/loongarch.h>
+#include <asm/export.h>
+
+#define RESUME_HOST (1 << 1)
+
+#define PT_GPR_OFFSET(x) (PT_R0 + 8*x)
+#define CONFIG_GUEST_CRMD ((1 << CSR_CRMD_DACM_SHIFT) | \
+ (1 << CSR_CRMD_DACF_SHIFT) | \
+ CSR_CRMD_PG | PLV_KERN)
+ .text
+
+.macro kvm_save_host_gpr base
+ .irp n,1,2,3,22,23,24,25,26,27,28,29,30,31
+ st.d $r\n, \base, PT_GPR_OFFSET(\n)
+ .endr
+.endm
+
+.macro kvm_restore_host_gpr base
+ .irp n,1,2,3,22,23,24,25,26,27,28,29,30,31
+ ld.d $r\n, \base, PT_GPR_OFFSET(\n)
+ .endr
+.endm
+
+/*
+ * prepare switch to guest
+ * @param:
+ * KVM_ARCH: kvm_vcpu_arch, don't touch it until 'ertn'
+ * GPRNUM: KVM_ARCH gpr number
+ * tmp, tmp1: temp register
+ */
+.macro kvm_switch_to_guest KVM_ARCH GPRNUM tmp tmp1
+ /* set host excfg.VS=0, all exceptions share one exception entry */
+ csrrd \tmp, LOONGARCH_CSR_ECFG
+ bstrins.w \tmp, zero, CSR_ECFG_VS_SHIFT_END, CSR_ECFG_VS_SHIFT
+ csrwr \tmp, LOONGARCH_CSR_ECFG
+
+ /* Load up the new EENTRY */
+ ld.d \tmp, \KVM_ARCH, KVM_ARCH_GEENTRY
+ csrwr \tmp, LOONGARCH_CSR_EENTRY
+
+ /* Set Guest ERA */
+ ld.d \tmp, \KVM_ARCH, KVM_ARCH_GPC
+ csrwr \tmp, LOONGARCH_CSR_ERA
+
+ /* Save host PGDL */
+ csrrd \tmp, LOONGARCH_CSR_PGDL
+ st.d \tmp, \KVM_ARCH, KVM_ARCH_HPGD
+
+ /* Switch to kvm */
+ ld.d \tmp1, \KVM_ARCH, KVM_VCPU_KVM - KVM_VCPU_ARCH
+
+ /* Load guest PGDL */
+ lu12i.w \tmp, KVM_GPGD
+ srli.w \tmp, \tmp, 12
+ ldx.d \tmp, \tmp1, \tmp
+ csrwr \tmp, LOONGARCH_CSR_PGDL
+
+ /* Mix GID and RID */
+ csrrd \tmp1, LOONGARCH_CSR_GSTAT
+ bstrpick.w \tmp1, \tmp1, CSR_GSTAT_GID_SHIFT_END, CSR_GSTAT_GID_SHIFT
+ csrrd \tmp, LOONGARCH_CSR_GTLBC
+ bstrins.w \tmp, \tmp1, CSR_GTLBC_TGID_SHIFT_END, CSR_GTLBC_TGID_SHIFT
+ csrwr \tmp, LOONGARCH_CSR_GTLBC
+
+ /*
+ * Switch to guest:
+ * GSTAT.PGM = 1, ERRCTL.ISERR = 0, TLBRPRMD.ISTLBR = 0
+ * ertn
+ */
+
+ /* Prepare enable Intr before enter guest */
+ ori \tmp, zero, CSR_PRMD_PIE
+ csrxchg \tmp, \tmp, LOONGARCH_CSR_PRMD
+
+ /* Set PVM bit to setup ertn to guest context */
+ ori \tmp, zero, CSR_GSTAT_PVM
+ csrxchg \tmp, \tmp, LOONGARCH_CSR_GSTAT
+
+ /* Load Guest gprs */
+ ld.d $r1, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 1)
+ ld.d $r2, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 2)
+ ld.d $r3, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 3)
+ ld.d $r4, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 4)
+ ld.d $r5, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 5)
+ ld.d $r7, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 7)
+ ld.d $r8, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 8)
+ ld.d $r9, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 9)
+ ld.d $r10, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 10)
+ ld.d $r11, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 11)
+ ld.d $r12, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 12)
+ ld.d $r13, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 13)
+ ld.d $r14, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 14)
+ ld.d $r15, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 15)
+ ld.d $r16, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 16)
+ ld.d $r17, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 17)
+ ld.d $r18, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 18)
+ ld.d $r19, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 19)
+ ld.d $r20, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 20)
+ ld.d $r21, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 21)
+ ld.d $r22, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 22)
+ ld.d $r23, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 23)
+ ld.d $r24, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 24)
+ ld.d $r25, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 25)
+ ld.d $r26, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 26)
+ ld.d $r27, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 27)
+ ld.d $r28, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 28)
+ ld.d $r29, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 29)
+ ld.d $r30, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 30)
+ ld.d $r31, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * 31)
+ /* Load KVM_ARCH register */
+ ld.d \KVM_ARCH, \KVM_ARCH, (KVM_ARCH_GGPR + 8 * \GPRNUM)
+
+ ertn
+.endm
+
+/* load kvm_vcpu to a2 and store a1 for free use */
+ .section .text
+ .cfi_sections .debug_frame
+SYM_CODE_START(kvm_vector_entry)
+ csrwr a2, KVM_TEMP_KS
+ csrrd a2, KVM_VCPU_KS
+ addi.d a2, a2, KVM_VCPU_ARCH
+
+ /* After save gprs, free to use any gpr */
+ st.d $r1, a2, (KVM_ARCH_GGPR + 8 * 1)
+ st.d $r2, a2, (KVM_ARCH_GGPR + 8 * 2)
+ st.d $r3, a2, (KVM_ARCH_GGPR + 8 * 3)
+ st.d $r4, a2, (KVM_ARCH_GGPR + 8 * 4)
+ st.d $r5, a2, (KVM_ARCH_GGPR + 8 * 5)
+ st.d $r7, a2, (KVM_ARCH_GGPR + 8 * 7)
+ st.d $r8, a2, (KVM_ARCH_GGPR + 8 * 8)
+ st.d $r9, a2, (KVM_ARCH_GGPR + 8 * 9)
+ st.d $r10, a2, (KVM_ARCH_GGPR + 8 * 10)
+ st.d $r11, a2, (KVM_ARCH_GGPR + 8 * 11)
+ st.d $r12, a2, (KVM_ARCH_GGPR + 8 * 12)
+ st.d $r13, a2, (KVM_ARCH_GGPR + 8 * 13)
+ st.d $r14, a2, (KVM_ARCH_GGPR + 8 * 14)
+ st.d $r15, a2, (KVM_ARCH_GGPR + 8 * 15)
+ st.d $r16, a2, (KVM_ARCH_GGPR + 8 * 16)
+ st.d $r17, a2, (KVM_ARCH_GGPR + 8 * 17)
+ st.d $r18, a2, (KVM_ARCH_GGPR + 8 * 18)
+ st.d $r19, a2, (KVM_ARCH_GGPR + 8 * 19)
+ st.d $r20, a2, (KVM_ARCH_GGPR + 8 * 20)
+ st.d $r21, a2, (KVM_ARCH_GGPR + 8 * 21)
+ st.d $r22, a2, (KVM_ARCH_GGPR + 8 * 22)
+ st.d $r23, a2, (KVM_ARCH_GGPR + 8 * 23)
+ st.d $r24, a2, (KVM_ARCH_GGPR + 8 * 24)
+ st.d $r25, a2, (KVM_ARCH_GGPR + 8 * 25)
+ st.d $r26, a2, (KVM_ARCH_GGPR + 8 * 26)
+ st.d $r27, a2, (KVM_ARCH_GGPR + 8 * 27)
+ st.d $r28, a2, (KVM_ARCH_GGPR + 8 * 28)
+ st.d $r29, a2, (KVM_ARCH_GGPR + 8 * 29)
+ st.d $r30, a2, (KVM_ARCH_GGPR + 8 * 30)
+ st.d $r31, a2, (KVM_ARCH_GGPR + 8 * 31)
+ /* Save guest a2 */
+ csrrd t0, KVM_TEMP_KS
+ st.d t0, a2, (KVM_ARCH_GGPR + 8 * REG_A2)
+
+ /* a2: kvm_vcpu_arch, a1 is free to use */
+ csrrd s1, KVM_VCPU_KS
+ ld.d s0, s1, KVM_VCPU_RUN
+
+ csrrd t0, LOONGARCH_CSR_ESTAT
+ st.d t0, a2, KVM_ARCH_HESTAT
+ csrrd t0, LOONGARCH_CSR_ERA
+ st.d t0, a2, KVM_ARCH_GPC
+ csrrd t0, LOONGARCH_CSR_BADV
+ st.d t0, a2, KVM_ARCH_HBADV
+ csrrd t0, LOONGARCH_CSR_BADI
+ st.d t0, a2, KVM_ARCH_HBADI
+
+ /* Restore host excfg.VS */
+ csrrd t0, LOONGARCH_CSR_ECFG
+ ld.d t1, a2, KVM_ARCH_HECFG
+ or t0, t0, t1
+ csrwr t0, LOONGARCH_CSR_ECFG
+
+ /* Restore host eentry */
+ ld.d t0, a2, KVM_ARCH_HEENTRY
+ csrwr t0, LOONGARCH_CSR_EENTRY
+
+#if defined(CONFIG_CPU_HAS_FPU)
+ /* Save FPU context */
+ csrrd t0, LOONGARCH_CSR_EUEN
+ ori t1, zero, CSR_EUEN_FPEN
+ and t2, t0, t1
+ beqz t2, 1f
+ movfcsr2gr t3, fcsr0
+ st.d t3, a2, VCPU_FCSR0
+
+ movcf2gr t3, $fcc0
+ or t2, t3, zero
+ movcf2gr t3, $fcc1
+ bstrins.d t2, t3, 0xf, 0x8
+ movcf2gr t3, $fcc2
+ bstrins.d t2, t3, 0x17, 0x10
+ movcf2gr t3, $fcc3
+ bstrins.d t2, t3, 0x1f, 0x18
+ movcf2gr t3, $fcc4
+ bstrins.d t2, t3, 0x27, 0x20
+ movcf2gr t3, $fcc5
+ bstrins.d t2, t3, 0x2f, 0x28
+ movcf2gr t3, $fcc6
+ bstrins.d t2, t3, 0x37, 0x30
+ movcf2gr t3, $fcc7
+ bstrins.d t2, t3, 0x3f, 0x38
+ st.d t2, a2, VCPU_FCC
+ movgr2fcsr fcsr0, zero
+1:
+#endif
+ ld.d t0, a2, KVM_ARCH_HPGD
+ csrwr t0, LOONGARCH_CSR_PGDL
+
+ /* Disable PVM bit for keeping from into guest */
+ ori t0, zero, CSR_GSTAT_PVM
+ csrxchg zero, t0, LOONGARCH_CSR_GSTAT
+ /* Clear GTLBC.TGID field */
+ csrrd t0, LOONGARCH_CSR_GTLBC
+ bstrins.w t0, zero, CSR_GTLBC_TGID_SHIFT_END, CSR_GTLBC_TGID_SHIFT
+ csrwr t0, LOONGARCH_CSR_GTLBC
+ /* Enable Address Map mode */
+ ori t0, zero, CONFIG_GUEST_CRMD
+ csrwr t0, LOONGARCH_CSR_CRMD
+ ld.d tp, a2, KVM_ARCH_HGP
+ ld.d sp, a2, KVM_ARCH_HSTACK
+ /* restore per cpu register */
+ ld.d $r21, a2, KVM_ARCH_HPERCPU
+ addi.d sp, sp, -PT_SIZE
+
+ /* Prepare handle exception */
+ or a0, s0, zero
+ or a1, s1, zero
+ ld.d t8, a2, KVM_ARCH_HANDLE_EXIT
+ jirl ra,t8, 0
+
+ ori t0, zero, CSR_CRMD_IE
+ csrxchg zero, t0, LOONGARCH_CSR_CRMD
+ or a2, s1, zero
+ addi.d a2, a2, KVM_VCPU_ARCH
+
+ andi t0, a0, RESUME_HOST
+ bnez t0, ret_to_host
+
+ /*
+ * return to guest
+ * save per cpu register again, maybe switched to another cpu
+ */
+ st.d $r21, a2, KVM_ARCH_HPERCPU
+
+ /* Save kvm_vcpu to kscratch */
+ csrwr s1, KVM_VCPU_KS
+ kvm_switch_to_guest a2 REG_A2 t0 t1
+
+ret_to_host:
+ ld.d a2, a2, KVM_ARCH_HSTACK
+ addi.d a2, a2, -PT_SIZE
+ srai.w a3, a0, 2
+ or a0, a3, zero
+ kvm_restore_host_gpr a2
+ jirl zero, ra, 0
+SYM_CODE_END(kvm_vector_entry)
+kvm_vector_entry_end:
+
+/*
+ * int kvm_enter_guest(struct kvm_run *run, struct kvm_vcpu *vcpu)
+ *
+ * @register_param:
+ * a0: kvm_run* run
+ * a1: kvm_vcpu* vcpu
+ */
+SYM_FUNC_START(kvm_enter_guest)
+ /* allocate space in stack bottom */
+ addi.d a2, sp, -PT_SIZE
+ /* save host gprs */
+ kvm_save_host_gpr a2
+
+ /* save host crmd,prmd csr to stack */
+ csrrd a3, LOONGARCH_CSR_CRMD
+ st.d a3, a2, PT_CRMD
+ csrrd a3, LOONGARCH_CSR_PRMD
+ st.d a3, a2, PT_PRMD
+
+ addi.d a2, a1, KVM_VCPU_ARCH
+ st.d sp, a2, KVM_ARCH_HSTACK
+ st.d tp, a2, KVM_ARCH_HGP
+ /* Save per cpu register */
+ st.d $r21, a2, KVM_ARCH_HPERCPU
+
+ /* Save kvm_vcpu to kscratch */
+ csrwr a1, KVM_VCPU_KS
+ kvm_switch_to_guest a2 REG_A2 t0 t1
+SYM_FUNC_END(kvm_enter_guest)
+kvm_enter_guest_end:
+
+ .section ".rodata"
+SYM_DATA(kvm_vector_size,
+ .quad kvm_vector_entry_end - kvm_vector_entry)
+SYM_DATA(kvm_enter_guest_size,
+ .quad kvm_enter_guest_end - kvm_enter_guest)
+
+
+SYM_FUNC_START(kvm_save_fpu)
+ fpu_save_double a0 t1
+ jirl zero, ra, 0
+SYM_FUNC_END(kvm_save_fpu)
+
+SYM_FUNC_START(kvm_restore_fpu)
+ fpu_restore_double a0 t1
+ jirl zero, ra, 0
+SYM_FUNC_END(kvm_restore_fpu)
+
+SYM_FUNC_START(kvm_restore_fcsr)
+ fpu_restore_csr a0 t1
+ fpu_restore_cc a0 t1 t2
+
+ jirl zero, ra, 0
+SYM_FUNC_END(kvm_restore_fcsr)
--
2.31.1