diff mbox series

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

Message ID 20240719160913.342027-5-apatel@ventanamicro.com (mailing list archive)
State New, archived
Headers show
Series Accelerate KVM RISC-V when running as a guest | expand

Commit Message

Anup Patel July 19, 2024, 4:09 p.m. UTC 
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(-)

Comments

Atish Patra Oct. 16, 2024, 9:37 p.m. UTC | #1 
On Fri, Jul 19, 2024 at 9:09 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> 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
>

Reviewed-by: Atish Patra <atishp@rivosinc.com>
diff mbox series

Patch

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