[PATCH 04/13] RISC-V: KVM: Break down the __kvm_riscv_switch_to() into macros

Anup Patel
2024-07-19T16:09:39Z

Break down the __kvm_riscv_switch_to() function into macros so that
these macros can be later re-used by SBI NACL extension based low-level
switch function.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
arch/riscv/kvm/vcpu_switch.S | 52 +++++++++++++++++++++++++++---------
1 file changed, 40 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index 3f8cbc21a644..9f13e5ce6a18 100644
--- a/arch/riscv/kvm/vcpu_switch.S
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -11,11 +11,7 @@
#include <asm/asm-offsets.h>
#include <asm/csr.h>

- .text
- .altmacro
- .option norelax
-
-SYM_FUNC_START(__kvm_riscv_switch_to)
+.macro SAVE_HOST_GPRS
/* Save Host GPRs (except A0 and T0-T6) */
REG_S ra, (KVM_ARCH_HOST_RA)(a0)
REG_S sp, (KVM_ARCH_HOST_SP)(a0)
@@ -40,10 +36,12 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_S s9, (KVM_ARCH_HOST_S9)(a0)
REG_S s10, (KVM_ARCH_HOST_S10)(a0)
REG_S s11, (KVM_ARCH_HOST_S11)(a0)
+.endm

+.macro SAVE_HOST_AND_RESTORE_GUEST_CSRS __resume_addr
/* Load Guest CSR values */
REG_L t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
- la t1, .Lkvm_switch_return
+ la t1, \__resume_addr
REG_L t2, (KVM_ARCH_GUEST_SEPC)(a0)

/* Save Host and Restore Guest SSTATUS */
@@ -62,7 +60,9 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_S t0, (KVM_ARCH_HOST_SSTATUS)(a0)
REG_S t1, (KVM_ARCH_HOST_STVEC)(a0)
REG_S t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
+.endm

+.macro RESTORE_GUEST_GPRS
/* Restore Guest GPRs (except A0) */
REG_L ra, (KVM_ARCH_GUEST_RA)(a0)
REG_L sp, (KVM_ARCH_GUEST_SP)(a0)
@@ -97,13 +97,9 @@ SYM_FUNC_START(__kvm_riscv_switch_to)

/* Restore Guest A0 */
REG_L a0, (KVM_ARCH_GUEST_A0)(a0)
+.endm

- /* Resume Guest */
- sret
-
- /* Back to Host */
- .align 2
-.Lkvm_switch_return:
+.macro SAVE_GUEST_GPRS
/* Swap Guest A0 with SSCRATCH */
csrrw a0, CSR_SSCRATCH, a0

@@ -138,7 +134,9 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_S t4, (KVM_ARCH_GUEST_T4)(a0)
REG_S t5, (KVM_ARCH_GUEST_T5)(a0)
REG_S t6, (KVM_ARCH_GUEST_T6)(a0)
+.endm

+.macro SAVE_GUEST_AND_RESTORE_HOST_CSRS
/* Load Host CSR values */
REG_L t0, (KVM_ARCH_HOST_STVEC)(a0)
REG_L t1, (KVM_ARCH_HOST_SSCRATCH)(a0)
@@ -160,7 +158,9 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_S t1, (KVM_ARCH_GUEST_A0)(a0)
REG_S t2, (KVM_ARCH_GUEST_SSTATUS)(a0)
REG_S t3, (KVM_ARCH_GUEST_SEPC)(a0)
+.endm

+.macro RESTORE_HOST_GPRS
/* Restore Host GPRs (except A0 and T0-T6) */
REG_L ra, (KVM_ARCH_HOST_RA)(a0)
REG_L sp, (KVM_ARCH_HOST_SP)(a0)
@@ -185,6 +185,34 @@ SYM_FUNC_START(__kvm_riscv_switch_to)
REG_L s9, (KVM_ARCH_HOST_S9)(a0)
REG_L s10, (KVM_ARCH_HOST_S10)(a0)
REG_L s11, (KVM_ARCH_HOST_S11)(a0)
+.endm
+
+ .text
+ .altmacro
+ .option norelax
+
+ /*
+ * Parameters:
+ * A0 <= Pointer to struct kvm_vcpu_arch
+ */
+SYM_FUNC_START(__kvm_riscv_switch_to)
+ SAVE_HOST_GPRS
+
+ SAVE_HOST_AND_RESTORE_GUEST_CSRS .Lkvm_switch_return
+
+ RESTORE_GUEST_GPRS
+
+ /* Resume Guest using SRET */
+ sret
+
+ /* Back to Host */
+ .align 2
+.Lkvm_switch_return:
+ SAVE_GUEST_GPRS
+
+ SAVE_GUEST_AND_RESTORE_HOST_CSRS
+
+ RESTORE_HOST_GPRS

/* Return to C code */
ret
--
2.34.1