[Qemu-devel] Re: [PATCH 0/9] S390x KVM support

[Carsten Otte]

Alexander Graf wrote:
> This is the resulting code. Please comment on things you like and also on the
> ones you don't :-).
I've reviewed and tested it, great work Alex :-)

> Also to actually run this code you need a patch for an ugly bug in the kernel
> module: http://alex.csgraf.de/psw.patch
Well, it was not exactly a bug. Kuli does'nt need the psw to be updated 
in kvm_run at all times. Your hotfix updates the psw in a union, even if 
the exit reason indicates that s390_sieic is not valid. The patch at the 
end of this mail moves the PSW out of the union. I think it makes most 
sense if Avi picks this patch and you adopt your series to it. This way 
the user interface of the kvm module works for both kuli and qemu.







This patch moves s390 processor status word into the base kvm_run
struct and keeps it up-to date on all userspace exits.

Signed-off-by: Carsten Otte <address@hidden>
---
arch/s390/kvm/kvm-s390.c |   14 ++++++++------
include/linux/kvm.h      |    8 ++++++--
2 files changed, 14 insertions(+), 8 deletions(-)

Index: kvm/include/linux/kvm.h
===================================================================
--- kvm.orig/include/linux/kvm.h        2009-10-20 15:00:40.000000000 +0200
+++ kvm/include/linux/kvm.h     2009-10-20 16:51:48.000000000 +0200
@@ -7,6 +7,7 @@
 * Note: you must update KVM_API_VERSION if you change this interface.
 */

+#include <linux/autoconf.h>
#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/ioctl.h>
@@ -116,6 +117,11 @@
        __u64 cr8;
        __u64 apic_base;

+#ifdef CONFIG_S390
+       /* the processor status word for s390 */
+       __u64 psw_mask; /* psw upper half */
+       __u64 psw_addr; /* psw lower half */
+#endif
        union {
                /* KVM_EXIT_UNKNOWN */
                struct {
@@ -167,8 +173,6 @@
                /* KVM_EXIT_S390_SIEIC */
                struct {
                        __u8 icptcode;
-                       __u64 mask; /* psw upper half */
-                       __u64 addr; /* psw lower half */
                        __u16 ipa;
                        __u32 ipb;
                } s390_sieic;
Index: kvm/arch/s390/kvm/kvm-s390.c
===================================================================
--- kvm.orig/arch/s390/kvm/kvm-s390.c   2009-10-20 15:01:02.000000000 +0200
+++ kvm/arch/s390/kvm/kvm-s390.c        2009-10-20 18:13:45.000000000 +0200
@@ -421,7 +421,8 @@
        if (atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_RUNNING)
                rc = -EBUSY;
        else
-               vcpu->arch.sie_block->gpsw = psw;
+               vcpu->run->psw_mask = psw.mask;
+               vcpu->run->psw_addr = psw.addr;
        vcpu_put(vcpu);
        return rc;
}
@@ -509,9 +510,6 @@

        switch (kvm_run->exit_reason) {
        case KVM_EXIT_S390_SIEIC:
-               vcpu->arch.sie_block->gpsw.mask = kvm_run->s390_sieic.mask;
-               vcpu->arch.sie_block->gpsw.addr = kvm_run->s390_sieic.addr;
-               break;
        case KVM_EXIT_UNKNOWN:
        case KVM_EXIT_INTR:
        case KVM_EXIT_S390_RESET:
@@ -520,6 +518,9 @@
                BUG();
        }

+       vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
+       vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
+
        might_fault();

        do {
@@ -539,8 +540,6 @@
                /* intercept cannot be handled in-kernel, prepare kvm-run */
                kvm_run->exit_reason         = KVM_EXIT_S390_SIEIC;
                kvm_run->s390_sieic.icptcode = vcpu->arch.sie_block->icptcode;
-               kvm_run->s390_sieic.mask     = vcpu->arch.sie_block->gpsw.mask;
-               kvm_run->s390_sieic.addr     = vcpu->arch.sie_block->gpsw.addr;
                kvm_run->s390_sieic.ipa      = vcpu->arch.sie_block->ipa;
                kvm_run->s390_sieic.ipb      = vcpu->arch.sie_block->ipb;
                rc = 0;
@@ -552,6 +551,9 @@
                rc = 0;
        }

+       kvm_run->psw_mask     = vcpu->arch.sie_block->gpsw.mask;
+       kvm_run->psw_addr     = vcpu->arch.sie_block->gpsw.addr;
+
        if (vcpu->sigset_active)
                sigprocmask(SIG_SETMASK, &sigsaved, NULL);