[PATCH v3 0/3] riscv: kvm: use generic entry for TIF_NOTIFY_RESUME and misc

[PATCH v3 0/3] riscv: kvm: use generic entry for TIF_NOTIFY_RESUME and misc

[Jisheng Zhang]

This series is a preparation series to add PREEMPT_RT support to riscv:
patch1 adds the missing number of signal exits in vCPU stat
patch2 switches to the generic guest entry infrastructure
patch3 select HAVE_POSIX_CPU_TIMERS_TASK_WORK which is a requirement for
RT

After these three patches merged, the left RT patches are similar as
other arch.

Since v2:
  - splict the series into two separate ones, one for next another for
    RT.

Since v1:
  - send to related maillist, I press ENTER too quickly when sending v1
  - remove the signal_pending() handling because that's covered by
    generic guest entry infrastructure

Jisheng Zhang (3):
  RISC-V: KVM: Record number of signal exits as a vCPU stat
  RISC-V: KVM: Use generic guest entry infrastructure
  riscv: select HAVE_POSIX_CPU_TIMERS_TASK_WORK

 arch/riscv/Kconfig                |  1 +
 arch/riscv/include/asm/kvm_host.h |  1 +
 arch/riscv/kvm/Kconfig            |  1 +
 arch/riscv/kvm/vcpu.c             | 18 +++++++-----------
 4 files changed, 10 insertions(+), 11 deletions(-)

-- 
2.34.1

[PATCH v3 1/3] RISC-V: KVM: Record number of signal exits as a vCPU stat

[Jisheng Zhang]

Record a statistic indicating the number of times a vCPU has exited
due to a pending signal.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/include/asm/kvm_host.h | 1 +
 arch/riscv/kvm/vcpu.c             | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 60c517e4d576..dbbf43d52623 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -67,6 +67,7 @@ struct kvm_vcpu_stat {
 	u64 mmio_exit_kernel;
 	u64 csr_exit_user;
 	u64 csr_exit_kernel;
+	u64 signal_exits;
 	u64 exits;
 };
 
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index d0f08d5b4282..3da459fedc28 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -28,6 +28,7 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
 	STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
 	STATS_DESC_COUNTER(VCPU, csr_exit_user),
 	STATS_DESC_COUNTER(VCPU, csr_exit_kernel),
+	STATS_DESC_COUNTER(VCPU, signal_exits),
 	STATS_DESC_COUNTER(VCPU, exits)
 };
 
@@ -973,6 +974,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		if (signal_pending(current)) {
 			ret = -EINTR;
 			run->exit_reason = KVM_EXIT_INTR;
+			++vcpu->stat.signal_exits;
 		}
 
 		/*
-- 
2.34.1

[PATCH v3 2/3] RISC-V: KVM: Use generic guest entry infrastructure

[Jisheng Zhang]

Use generic guest entry infrastructure to properly handle
TIF_NOTIFY_RESUME.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/kvm/Kconfig |  1 +
 arch/riscv/kvm/vcpu.c  | 18 ++++++------------
 2 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
index f5a342fa1b1d..f36a737d5f96 100644
--- a/arch/riscv/kvm/Kconfig
+++ b/arch/riscv/kvm/Kconfig
@@ -24,6 +24,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select KVM_MMIO
 	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	select KVM_XFER_TO_GUEST_WORK
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select HAVE_KVM_EVENTFD
 	select SRCU
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 3da459fedc28..e3e6b8608288 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/entry-kvm.h>
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/kdebug.h>
@@ -959,7 +960,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	run->exit_reason = KVM_EXIT_UNKNOWN;
 	while (ret > 0) {
 		/* Check conditions before entering the guest */
-		cond_resched();
+		ret = xfer_to_guest_mode_handle_work(vcpu);
+		if (!ret)
+			ret = 1;
 
 		kvm_riscv_gstage_vmid_update(vcpu);
 
@@ -967,16 +970,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		local_irq_disable();
 
-		/*
-		 * Exit if we have a signal pending so that we can deliver
-		 * the signal to user space.
-		 */
-		if (signal_pending(current)) {
-			ret = -EINTR;
-			run->exit_reason = KVM_EXIT_INTR;
-			++vcpu->stat.signal_exits;
-		}
-
 		/*
 		 * Ensure we set mode to IN_GUEST_MODE after we disable
 		 * interrupts and before the final VCPU requests check.
@@ -999,7 +992,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		if (ret <= 0 ||
 		    kvm_riscv_gstage_vmid_ver_changed(&vcpu->kvm->arch.vmid) ||
-		    kvm_request_pending(vcpu)) {
+		    kvm_request_pending(vcpu) ||
+		    xfer_to_guest_mode_work_pending()) {
 			vcpu->mode = OUTSIDE_GUEST_MODE;
 			local_irq_enable();
 			kvm_vcpu_srcu_read_lock(vcpu);
-- 
2.34.1

[PATCH v3 3/3] riscv: select HAVE_POSIX_CPU_TIMERS_TASK_WORK

[Jisheng Zhang]

Move POSIX CPU timer expiry and signal delivery into task context to
allow PREEMPT_RT setups to coexist with KVM.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 79e52441e18b..7a8134fd7ec9 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -104,6 +104,7 @@ config RISCV
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select HAVE_STACKPROTECTOR
-- 
2.34.1

Re: [PATCH v3 1/3] RISC-V: KVM: Record number of signal exits as a vCPU stat

[Guo Ren]

Reviewed-by: Guo Ren <guoren@kernel.org>

➜  linux git:(master) grep signal_exits arch/arm64 -r
arch/arm64/kvm/guest.c: STATS_DESC_COUNTER(VCPU, signal_exits),
arch/arm64/include/asm/kvm_host.h:      u64 signal_exits;

By the way, do you know why arm64 is defined, but not used?


On Mon, Sep 26, 2022 at 12:33 AM Jisheng Zhang <jszhang@kernel.org> wrote:
>
> Record a statistic indicating the number of times a vCPU has exited
> due to a pending signal.
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/include/asm/kvm_host.h | 1 +
>  arch/riscv/kvm/vcpu.c             | 2 ++
>  2 files changed, 3 insertions(+)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 60c517e4d576..dbbf43d52623 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -67,6 +67,7 @@ struct kvm_vcpu_stat {
>         u64 mmio_exit_kernel;
>         u64 csr_exit_user;
>         u64 csr_exit_kernel;
> +       u64 signal_exits;
>         u64 exits;
>  };
>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index d0f08d5b4282..3da459fedc28 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -28,6 +28,7 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
>         STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
>         STATS_DESC_COUNTER(VCPU, csr_exit_user),
>         STATS_DESC_COUNTER(VCPU, csr_exit_kernel),
> +       STATS_DESC_COUNTER(VCPU, signal_exits),
>         STATS_DESC_COUNTER(VCPU, exits)
>  };
>
> @@ -973,6 +974,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>                 if (signal_pending(current)) {
>                         ret = -EINTR;
>                         run->exit_reason = KVM_EXIT_INTR;
> +                       ++vcpu->stat.signal_exits;
>                 }
>
>                 /*
> --
> 2.34.1
>


--
Best Regards
 Guo Ren

Re: [PATCH v3 1/3] RISC-V: KVM: Record number of signal exits as a vCPU stat

[Andrew Jones]

On Wed, Sep 28, 2022 at 01:18:01PM +0800, Guo Ren wrote:
> Reviewed-by: Guo Ren <guoren@kernel.org>
> 
> ➜  linux git:(master) grep signal_exits arch/arm64 -r
> arch/arm64/kvm/guest.c: STATS_DESC_COUNTER(VCPU, signal_exits),
> arch/arm64/include/asm/kvm_host.h:      u64 signal_exits;
> 
> By the way, do you know why arm64 is defined, but not used?

It is. arm64 uses generic xfer to guest mode work, like this series
introduces for riscv.

Thanks,
drew

> 
> 
> On Mon, Sep 26, 2022 at 12:33 AM Jisheng Zhang <jszhang@kernel.org> wrote:
> >
> > Record a statistic indicating the number of times a vCPU has exited
> > due to a pending signal.
> >
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> >  arch/riscv/include/asm/kvm_host.h | 1 +
> >  arch/riscv/kvm/vcpu.c             | 2 ++
> >  2 files changed, 3 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> > index 60c517e4d576..dbbf43d52623 100644
> > --- a/arch/riscv/include/asm/kvm_host.h
> > +++ b/arch/riscv/include/asm/kvm_host.h
> > @@ -67,6 +67,7 @@ struct kvm_vcpu_stat {
> >         u64 mmio_exit_kernel;
> >         u64 csr_exit_user;
> >         u64 csr_exit_kernel;
> > +       u64 signal_exits;
> >         u64 exits;
> >  };
> >
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index d0f08d5b4282..3da459fedc28 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -28,6 +28,7 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
> >         STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
> >         STATS_DESC_COUNTER(VCPU, csr_exit_user),
> >         STATS_DESC_COUNTER(VCPU, csr_exit_kernel),
> > +       STATS_DESC_COUNTER(VCPU, signal_exits),
> >         STATS_DESC_COUNTER(VCPU, exits)
> >  };
> >
> > @@ -973,6 +974,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> >                 if (signal_pending(current)) {
> >                         ret = -EINTR;
> >                         run->exit_reason = KVM_EXIT_INTR;
> > +                       ++vcpu->stat.signal_exits;
> >                 }
> >
> >                 /*
> > --
> > 2.34.1
> >
> 
> 
> --
> Best Regards
>  Guo Ren
> 
> -- 
> kvm-riscv mailing list
> kvm-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kvm-riscv

Re: [PATCH v3 0/3] riscv: kvm: use generic entry for TIF_NOTIFY_RESUME and misc

[Andrew Jones]

On Mon, Sep 26, 2022 at 12:23:57AM +0800, Jisheng Zhang wrote:
> This series is a preparation series to add PREEMPT_RT support to riscv:
> patch1 adds the missing number of signal exits in vCPU stat
> patch2 switches to the generic guest entry infrastructure
> patch3 select HAVE_POSIX_CPU_TIMERS_TASK_WORK which is a requirement for
> RT
> 
> After these three patches merged, the left RT patches are similar as
> other arch.
> 
> Since v2:
>   - splict the series into two separate ones, one for next another for
>     RT.
> 
> Since v1:
>   - send to related maillist, I press ENTER too quickly when sending v1
>   - remove the signal_pending() handling because that's covered by
>     generic guest entry infrastructure
> 
> Jisheng Zhang (3):
>   RISC-V: KVM: Record number of signal exits as a vCPU stat
>   RISC-V: KVM: Use generic guest entry infrastructure
>   riscv: select HAVE_POSIX_CPU_TIMERS_TASK_WORK
> 
>  arch/riscv/Kconfig                |  1 +
>  arch/riscv/include/asm/kvm_host.h |  1 +
>  arch/riscv/kvm/Kconfig            |  1 +
>  arch/riscv/kvm/vcpu.c             | 18 +++++++-----------
>  4 files changed, 10 insertions(+), 11 deletions(-)
> 
> -- 
> 2.34.1
>

For the series

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Re: [PATCH v3 0/3] riscv: kvm: use generic entry for TIF_NOTIFY_RESUME and misc

[Anup Patel]

On Sun, Sep 25, 2022 at 10:03 PM Jisheng Zhang <jszhang@kernel.org> wrote:
>
> This series is a preparation series to add PREEMPT_RT support to riscv:
> patch1 adds the missing number of signal exits in vCPU stat
> patch2 switches to the generic guest entry infrastructure
> patch3 select HAVE_POSIX_CPU_TIMERS_TASK_WORK which is a requirement for
> RT
>
> After these three patches merged, the left RT patches are similar as
> other arch.
>
> Since v2:
>   - splict the series into two separate ones, one for next another for
>     RT.
>
> Since v1:
>   - send to related maillist, I press ENTER too quickly when sending v1
>   - remove the signal_pending() handling because that's covered by
>     generic guest entry infrastructure
>
> Jisheng Zhang (3):
>   RISC-V: KVM: Record number of signal exits as a vCPU stat
>   RISC-V: KVM: Use generic guest entry infrastructure
>   riscv: select HAVE_POSIX_CPU_TIMERS_TASK_WORK

I have queued this series for Linux-6.1

Thanks,
Anup

>
>  arch/riscv/Kconfig                |  1 +
>  arch/riscv/include/asm/kvm_host.h |  1 +
>  arch/riscv/kvm/Kconfig            |  1 +
>  arch/riscv/kvm/vcpu.c             | 18 +++++++-----------
>  4 files changed, 10 insertions(+), 11 deletions(-)
>
> --
> 2.34.1
>