RISC-V: KVM: Break down the __kvm_riscv_switch_to() into macros

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>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-5-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
index 3f8cbc21a644f8c2a6a106d2445ac4de4e664c26..9f13e5ce6a18fce6bb5542b554efb7433f857ce3 100644 (file)
--- 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