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| author | Claudio Imbrenda <imbrenda@linux.ibm.com> | 2021-09-20 15:24:52 +0200 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2021-10-25 09:20:39 +0200 |
| commit | f0a1a0615a6ff6d38af2c65a522698fb4bb85df6 (patch) | |
| tree | 3e7603404c56abc27670b823b223c2e1d5435118 /arch/s390/kvm | |
| parent | 1e2aa46de526a5adafe580bca4c25856bb06f09e (diff) | |
| download | linux-f0a1a0615a6ff6d38af2c65a522698fb4bb85df6.tar.bz2 | |
KVM: s390: pv: avoid stalls when making pages secure
Improve make_secure_pte to avoid stalls when the system is heavily
overcommitted. This was especially problematic in kvm_s390_pv_unpack,
because of the loop over all pages that needed unpacking.
Due to the locks being held, it was not possible to simply replace
uv_call with uv_call_sched. A more complex approach was
needed, in which uv_call is replaced with __uv_call, which does not
loop. When the UVC needs to be executed again, -EAGAIN is returned, and
the caller (or its caller) will try again.
When -EAGAIN is returned, the path is the same as when the page is in
writeback (and the writeback check is also performed, which is
harmless).
Fixes: 214d9bbcd3a672 ("s390/mm: provide memory management functions for protected KVM guests")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Link: https://lore.kernel.org/r/20210920132502.36111-5-imbrenda@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'arch/s390/kvm')
| -rw-r--r-- | arch/s390/kvm/intercept.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c index 2bd8f854f1b4..d07ff646d844 100644 --- a/arch/s390/kvm/intercept.c +++ b/arch/s390/kvm/intercept.c @@ -518,6 +518,11 @@ static int handle_pv_uvc(struct kvm_vcpu *vcpu) */ if (rc == -EINVAL) return 0; + /* + * If we got -EAGAIN here, we simply return it. It will eventually + * get propagated all the way to userspace, which should then try + * again. + */ return rc; } |