Commit f771b557 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

KVM: PPC: Use KVM_CAP_PPC_AIL_MODE_3 

Use KVM_CAP_PPC_AIL_MODE_3 to advertise the capability to set the AIL
resource mode to 3 with the H_SET_MODE hypercall. This capability
differs between processor types and KVM types (PR, HV, Nested HV), and
affects guest-visible behaviour.

QEMU will implement a cap-ail-mode-3 to control this behaviour[1], and
use the KVM CAP if available to determine KVM support[2].

[1] https://lists.nongnu.org/archive/html/qemu-ppc/2022-02/msg00437.html
[2] https://lists.nongnu.org/archive/html/qemu-ppc/2022-02/msg00439.html



Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarFabiano Rosas <farosas@linux.ibm.com>
[mpe: Rebase onto 93b71801 from kvm-ppc-cap-210 branch, add EXPORT_SYMBOL]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220222064727.2314380-4-npiggin@gmail.com
parent 839d893b

arch/powerpc/include/asm/setup.h

+2 −0
Original line number Diff line number Diff line
@@ -28,11 +28,13 @@ void setup_panic(void); 
#define ARCH_PANIC_TIMEOUT 180



#ifdef CONFIG_PPC_PSERIES

extern bool pseries_reloc_on_exception(void);

extern bool pseries_enable_reloc_on_exc(void);

extern void pseries_disable_reloc_on_exc(void);

extern void pseries_big_endian_exceptions(void);

void __init pseries_little_endian_exceptions(void);

#else

static inline bool pseries_reloc_on_exception(void) { return false; }

static inline bool pseries_enable_reloc_on_exc(void) { return false; }

static inline void pseries_disable_reloc_on_exc(void) {}

static inline void pseries_big_endian_exceptions(void) {}

arch/powerpc/kvm/powerpc.c

+17 −0
Original line number Diff line number Diff line
@@ -705,6 +705,23 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) 
		r = 1;

		break;

#endif

	case KVM_CAP_PPC_AIL_MODE_3:

		r = 0;

		/*

		 * KVM PR, POWER7, and some POWER9s don't support AIL=3 mode.

		 * The POWER9s can support it if the guest runs in hash mode,

		 * but QEMU doesn't necessarily query the capability in time.

		 */

		if (hv_enabled) {

			if (kvmhv_on_pseries()) {

				if (pseries_reloc_on_exception())

					r = 1;

			} else if (cpu_has_feature(CPU_FTR_ARCH_207S) &&

				  !cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) {

				r = 1;

			}

		}

		break;

	default:

		r = 0;

		break;

arch/powerpc/platforms/pseries/setup.c

+12 −1
Original line number Diff line number Diff line
@@ -353,6 +353,14 @@ static void pseries_lpar_idle(void) 
	pseries_idle_epilog();

}



static bool pseries_reloc_on_exception_enabled;



bool pseries_reloc_on_exception(void)

{

	return pseries_reloc_on_exception_enabled;

}

EXPORT_SYMBOL_GPL(pseries_reloc_on_exception);



/*

 * Enable relocation on during exceptions. This has partition wide scope and

 * may take a while to complete, if it takes longer than one second we will
@@ -377,6 +385,7 @@ bool pseries_enable_reloc_on_exc(void) 
					" on exceptions: %ld\n", rc);

				return false;

			}

			pseries_reloc_on_exception_enabled = true;

			return true;

		}
@@ -404,7 +413,9 @@ void pseries_disable_reloc_on_exc(void) 
			break;

		mdelay(get_longbusy_msecs(rc));

	}

	if (rc != H_SUCCESS)

	if (rc == H_SUCCESS)

		pseries_reloc_on_exception_enabled = false;

	else

		pr_warn("Warning: Failed to disable relocation on exceptions: %ld\n",

			rc);

}