Re: [RFC PATCH 1/9] KVM: PPC: Book3S 64: move KVM interrupt entry to a common entry point

[Fabiano Rosas <farosas@linux.ibm.com>]

Nicholas Piggin <npiggin@gmail.com> writes:

> Rather than bifurcate the call depending on whether or not HV is
> possible, and have the HV entry test for PR, just make a single
> common point which does the demultiplexing. This makes it simpler
> to add another type of exit handler.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>

> ---
>  arch/powerpc/kernel/exceptions-64s.S    |  8 +-----
>  arch/powerpc/kvm/Makefile               |  3 +++
>  arch/powerpc/kvm/book3s_64_entry.S      | 34 +++++++++++++++++++++++++
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 ++------
>  4 files changed, 40 insertions(+), 16 deletions(-)
>  create mode 100644 arch/powerpc/kvm/book3s_64_entry.S
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index e02ad6fefa46..65659ea3cec4 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -212,7 +212,6 @@ do_define_int n
>  .endm
>
>  #ifdef CONFIG_KVM_BOOK3S_64_HANDLER
> -#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
>  /*
>   * All interrupts which set HSRR registers, as well as SRESET and MCE and
>   * syscall when invoked with "sc 1" switch to MSR[HV]=1 (HVMODE) to be taken,
> @@ -242,13 +241,8 @@ do_define_int n
>
>  /*
>   * If an interrupt is taken while a guest is running, it is immediately routed
> - * to KVM to handle. If both HV and PR KVM arepossible, KVM interrupts go first
> - * to kvmppc_interrupt_hv, which handles the PR guest case.
> + * to KVM to handle.
>   */
> -#define kvmppc_interrupt kvmppc_interrupt_hv
> -#else
> -#define kvmppc_interrupt kvmppc_interrupt_pr
> -#endif
>
>  .macro KVMTEST name
>  	lbz	r10,HSTATE_IN_GUEST(r13)
> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
> index 2bfeaa13befb..cdd119028f64 100644
> --- a/arch/powerpc/kvm/Makefile
> +++ b/arch/powerpc/kvm/Makefile
> @@ -59,6 +59,9 @@ kvm-pr-y := \
>  kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \
>  	tm.o
>
> +kvm-book3s_64-builtin-objs-y += \
> +	book3s_64_entry.o
> +
>  ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
>  kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \
>  	book3s_rmhandlers.o
> diff --git a/arch/powerpc/kvm/book3s_64_entry.S b/arch/powerpc/kvm/book3s_64_entry.S
> new file mode 100644
> index 000000000000..22e34b95f478
> --- /dev/null
> +++ b/arch/powerpc/kvm/book3s_64_entry.S
> @@ -0,0 +1,34 @@
> +#include <asm/cache.h>
> +#include <asm/ppc_asm.h>
> +#include <asm/kvm_asm.h>
> +#include <asm/reg.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/kvm_book3s_asm.h>
> +
> +/*
> + * We come here from the first-level interrupt handlers.
> + */
> +.global	kvmppc_interrupt
> +.balign IFETCH_ALIGN_BYTES
> +kvmppc_interrupt:
> +	/*
> +	 * Register contents:
> +	 * R12		= (guest CR << 32) | interrupt vector
> +	 * R13		= PACA
> +	 * guest R12 saved in shadow VCPU SCRATCH0
> +	 * guest R13 saved in SPRN_SCRATCH0
> +	 */
> +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> +	std	r9, HSTATE_SCRATCH2(r13)
> +	lbz	r9, HSTATE_IN_GUEST(r13)
> +	cmpwi	r9, KVM_GUEST_MODE_HOST_HV
> +	beq	kvmppc_bad_host_intr
> +#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> +	cmpwi	r9, KVM_GUEST_MODE_GUEST
> +	ld	r9, HSTATE_SCRATCH2(r13)
> +	beq	kvmppc_interrupt_pr
> +#endif
> +	b	kvmppc_interrupt_hv
> +#else
> +	b	kvmppc_interrupt_pr
> +#endif
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index 8cf1f69f442e..b9c4acd747f7 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1255,16 +1255,8 @@ kvmppc_interrupt_hv:
>  	 * R13		= PACA
>  	 * guest R12 saved in shadow VCPU SCRATCH0
>  	 * guest R13 saved in SPRN_SCRATCH0
> +	 * guest R9 saved in HSTATE_SCRATCH2
>  	 */
> -	std	r9, HSTATE_SCRATCH2(r13)
> -	lbz	r9, HSTATE_IN_GUEST(r13)
> -	cmpwi	r9, KVM_GUEST_MODE_HOST_HV
> -	beq	kvmppc_bad_host_intr
> -#ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
> -	cmpwi	r9, KVM_GUEST_MODE_GUEST
> -	ld	r9, HSTATE_SCRATCH2(r13)
> -	beq	kvmppc_interrupt_pr
> -#endif
>  	/* We're now back in the host but in guest MMU context */
>  	li	r9, KVM_GUEST_MODE_HOST_HV
>  	stb	r9, HSTATE_IN_GUEST(r13)
> @@ -3253,6 +3245,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_P9_TM_HV_ASSIST)
>   * cfar is saved in HSTATE_CFAR(r13)
>   * ppr is saved in HSTATE_PPR(r13)
>   */
> +.global kvmppc_bad_host_intr
>  kvmppc_bad_host_intr:
>  	/*
>  	 * Switch to the emergency stack, but start half-way down in