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Message-Id: <20230328123119.3649361-28-zhaotianrui@loongson.cn>
Date: Tue, 28 Mar 2023 20:31:17 +0800
From: Tianrui Zhao <zhaotianrui@...ngson.cn>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
Mark Brown <broonie@...nel.org>,
Alex Deucher <alexander.deucher@....com>,
Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn,
Xi Ruoyao <xry111@...111.site>, zhaotianrui@...ngson.cn
Subject: [PING PATCH v4 27/29] LoongArch: KVM: Implement vcpu world switch
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@...ngson.cn>
---
arch/loongarch/kernel/asm-offsets.c | 32 +++
arch/loongarch/kvm/switch.S | 303 ++++++++++++++++++++++++++++
2 files changed, 335 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..cc5192d3c
--- /dev/null
+++ b/arch/loongarch/kvm/switch.S
@@ -0,0 +1,303 @@
+/* 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 PT_GPR_OFFSET(x) (PT_R0 + 8*x)
+ .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 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, a2, KVM_ARCH_GEENTRY
+ csrwr \tmp, LOONGARCH_CSR_EENTRY
+
+ /* Set Guest ERA */
+ ld.d \tmp, a2, KVM_ARCH_GPC
+ csrwr \tmp, LOONGARCH_CSR_ERA
+
+ /* Save host PGDL */
+ csrrd \tmp, LOONGARCH_CSR_PGDL
+ st.d \tmp, a2, KVM_ARCH_HPGD
+
+ /* Switch to kvm */
+ ld.d \tmp1, a2, 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
+ */
+
+ /*
+ * Enable intr in root mode with future ertn so that host interrupt
+ * can be responsed during VM runs
+ * guest crmd comes from separate gcsr_CRMD register
+ */
+ 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 ra, a2, (KVM_ARCH_GGPR + 8 * REG_RA)
+ ld.d tp, a2, (KVM_ARCH_GGPR + 8 * REG_TP)
+ ld.d sp, a2, (KVM_ARCH_GGPR + 8 * REG_SP)
+ ld.d a0, a2, (KVM_ARCH_GGPR + 8 * REG_A0)
+ ld.d a1, a2, (KVM_ARCH_GGPR + 8 * REG_A1)
+ ld.d a3, a2, (KVM_ARCH_GGPR + 8 * REG_A3)
+ ld.d a4, a2, (KVM_ARCH_GGPR + 8 * REG_A4)
+ ld.d a5, a2, (KVM_ARCH_GGPR + 8 * REG_A5)
+ ld.d a6, a2, (KVM_ARCH_GGPR + 8 * REG_A6)
+ ld.d a7, a2, (KVM_ARCH_GGPR + 8 * REG_A7)
+ ld.d t0, a2, (KVM_ARCH_GGPR + 8 * REG_T0)
+ ld.d t1, a2, (KVM_ARCH_GGPR + 8 * REG_T1)
+ ld.d t2, a2, (KVM_ARCH_GGPR + 8 * REG_T2)
+ ld.d t3, a2, (KVM_ARCH_GGPR + 8 * REG_T3)
+ ld.d t4, a2, (KVM_ARCH_GGPR + 8 * REG_T4)
+ ld.d t5, a2, (KVM_ARCH_GGPR + 8 * REG_T5)
+ ld.d t6, a2, (KVM_ARCH_GGPR + 8 * REG_T6)
+ ld.d t7, a2, (KVM_ARCH_GGPR + 8 * REG_T7)
+ ld.d t8, a2, (KVM_ARCH_GGPR + 8 * REG_T8)
+ ld.d u0, a2, (KVM_ARCH_GGPR + 8 * REG_U0)
+ ld.d fp, a2, (KVM_ARCH_GGPR + 8 * REG_FP)
+ ld.d s0, a2, (KVM_ARCH_GGPR + 8 * REG_S0)
+ ld.d s1, a2, (KVM_ARCH_GGPR + 8 * REG_S1)
+ ld.d s2, a2, (KVM_ARCH_GGPR + 8 * REG_S2)
+ ld.d s3, a2, (KVM_ARCH_GGPR + 8 * REG_S3)
+ ld.d s4, a2, (KVM_ARCH_GGPR + 8 * REG_S4)
+ ld.d s5, a2, (KVM_ARCH_GGPR + 8 * REG_S5)
+ ld.d s6, a2, (KVM_ARCH_GGPR + 8 * REG_S6)
+ ld.d s7, a2, (KVM_ARCH_GGPR + 8 * REG_S7)
+ ld.d s8, a2, (KVM_ARCH_GGPR + 8 * REG_S8)
+ /* Load KVM_ARCH register */
+ ld.d a2, a2, (KVM_ARCH_GGPR + 8 * REG_A2)
+
+ ertn
+.endm
+
+ /*
+ * exception entry for general exception from guest mode
+ * - IRQ is disabled
+ * - kernel privilege in root mode
+ * - page mode keep unchanged from previous prmd in root mode
+ * - Fixme: tlb exception cannot happen since registers relative with TLB
+ * - is still in guest mode, such as pgd table/vmid registers etc,
+ * - will fix with hw page walk enabled in future
+ * load kvm_vcpu from reserved CSR KVM_VCPU_KS, and save a2 to KVM_TEMP_KS
+ */
+ .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 ra, a2, (KVM_ARCH_GGPR + 8 * REG_RA)
+ st.d tp, a2, (KVM_ARCH_GGPR + 8 * REG_TP)
+ st.d sp, a2, (KVM_ARCH_GGPR + 8 * REG_SP)
+ st.d a0, a2, (KVM_ARCH_GGPR + 8 * REG_A0)
+ st.d a1, a2, (KVM_ARCH_GGPR + 8 * REG_A1)
+ st.d a3, a2, (KVM_ARCH_GGPR + 8 * REG_A3)
+ st.d a4, a2, (KVM_ARCH_GGPR + 8 * REG_A4)
+ st.d a5, a2, (KVM_ARCH_GGPR + 8 * REG_A5)
+ st.d a6, a2, (KVM_ARCH_GGPR + 8 * REG_A6)
+ st.d a7, a2, (KVM_ARCH_GGPR + 8 * REG_A7)
+ st.d t0, a2, (KVM_ARCH_GGPR + 8 * REG_T0)
+ st.d t1, a2, (KVM_ARCH_GGPR + 8 * REG_T1)
+ st.d t2, a2, (KVM_ARCH_GGPR + 8 * REG_T2)
+ st.d t3, a2, (KVM_ARCH_GGPR + 8 * REG_T3)
+ st.d t4, a2, (KVM_ARCH_GGPR + 8 * REG_T4)
+ st.d t5, a2, (KVM_ARCH_GGPR + 8 * REG_T5)
+ st.d t6, a2, (KVM_ARCH_GGPR + 8 * REG_T6)
+ st.d t7, a2, (KVM_ARCH_GGPR + 8 * REG_T7)
+ st.d t8, a2, (KVM_ARCH_GGPR + 8 * REG_T8)
+ st.d u0, a2, (KVM_ARCH_GGPR + 8 * REG_U0)
+ st.d fp, a2, (KVM_ARCH_GGPR + 8 * REG_FP)
+ st.d s0, a2, (KVM_ARCH_GGPR + 8 * REG_S0)
+ st.d s1, a2, (KVM_ARCH_GGPR + 8 * REG_S1)
+ st.d s2, a2, (KVM_ARCH_GGPR + 8 * REG_S2)
+ st.d s3, a2, (KVM_ARCH_GGPR + 8 * REG_S3)
+ st.d s4, a2, (KVM_ARCH_GGPR + 8 * REG_S4)
+ st.d s5, a2, (KVM_ARCH_GGPR + 8 * REG_S5)
+ st.d s6, a2, (KVM_ARCH_GGPR + 8 * REG_S6)
+ st.d s7, a2, (KVM_ARCH_GGPR + 8 * REG_S7)
+ st.d s8, a2, (KVM_ARCH_GGPR + 8 * REG_S8)
+ /* 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
+
+ /* restore host pgd table */
+ ld.d t0, a2, KVM_ARCH_HPGD
+ csrwr t0, LOONGARCH_CSR_PGDL
+
+ /*
+ * Disable PGM bit to enter root mode by default with next ertn
+ */
+ ori t0, zero, CSR_GSTAT_PVM
+ csrxchg zero, t0, LOONGARCH_CSR_GSTAT
+ /*
+ * Clear GTLBC.TGID field
+ * 0: for root tlb update in future tlb instr
+ * others: for guest tlb update like gpa to hpa in future tlb instr
+ */
+ csrrd t0, LOONGARCH_CSR_GTLBC
+ bstrins.w t0, zero, CSR_GTLBC_TGID_SHIFT_END, CSR_GTLBC_TGID_SHIFT
+ csrwr t0, LOONGARCH_CSR_GTLBC
+ ld.d tp, a2, KVM_ARCH_HGP
+ ld.d sp, a2, KVM_ARCH_HSTACK
+ /* restore per cpu register */
+ ld.d u0, 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
+
+ or a2, s1, zero
+ addi.d a2, a2, KVM_VCPU_ARCH
+
+ /* resume host when ret <= 0 */
+ bge zero, a0, ret_to_host
+
+ /*
+ * return to guest
+ * save per cpu register again, maybe switched to another cpu
+ */
+ st.d u0, a2, KVM_ARCH_HPERCPU
+
+ /* Save kvm_vcpu to kscratch */
+ csrwr s1, KVM_VCPU_KS
+ kvm_switch_to_guest t0 t1
+
+ret_to_host:
+ ld.d a2, a2, KVM_ARCH_HSTACK
+ addi.d a2, a2, -PT_SIZE
+ 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 u0, a2, KVM_ARCH_HPERCPU
+
+ /* Save kvm_vcpu to kscratch */
+ csrwr a1, KVM_VCPU_KS
+ kvm_switch_to_guest 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_csr a0 t1
+ fpu_save_double a0 t1
+ fpu_save_cc a0 t1 t2
+ jirl zero, ra, 0
+SYM_FUNC_END(kvm_save_fpu)
+
+SYM_FUNC_START(kvm_restore_fpu)
+ fpu_restore_double a0 t1
+ fpu_restore_csr a0 t1
+ fpu_restore_cc a0 t1 t2
+ jirl zero, ra, 0
+SYM_FUNC_END(kvm_restore_fpu)
--
2.31.1
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