From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
We can avoid one unneeded SIE entry after we reported a fault to g2.
Theoretically, g2 resolves the fault and we can create the shadow mapping
directly, instead of failing again when entering the SIE.
Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
---
arch/s390/kvm/vsie.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 3ececbb..7482488 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -28,7 +28,9 @@ struct vsie_page {
struct kvm_s390_sie_block *scb_o; /* 0x0200 */
/* the shadow gmap in use by the vsie_page */
struct gmap *gmap; /* 0x0208 */
- __u8 reserved[0x0700 - 0x0210]; /* 0x0210 */
+ /* address of the last reported fault to guest2 */
+ unsigned long fault_addr; /* 0x0210 */
+ __u8 reserved[0x0700 - 0x0218]; /* 0x0218 */
struct kvm_s390_crypto_cb crycb; /* 0x0700 */
__u8 fac[S390_ARCH_FAC_LIST_SIZE_BYTE]; /* 0x0800 */
} __packed;
@@ -676,10 +678,27 @@ static int handle_fault(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
rc = inject_fault(vcpu, rc,
current->thread.gmap_addr,
current->thread.gmap_write_flag);
+ if (rc >= 0)
+ vsie_page->fault_addr = current->thread.gmap_addr;
}
return rc;
}
+/*
+ * Retry the previous fault that required guest 2 intervention. This avoids
+ * one superfluous SIE re-entry and direct exit.
+ *
+ * Will ignore any errors. The next SIE fault will do proper fault handling.
+ */
+static void handle_last_fault(struct kvm_vcpu *vcpu,
+ struct vsie_page *vsie_page)
+{
+ if (vsie_page->fault_addr)
+ kvm_s390_shadow_fault(vcpu, vsie_page->gmap,
+ vsie_page->fault_addr);
+ vsie_page->fault_addr = 0;
+}
+
static inline void clear_vsie_icpt(struct vsie_page *vsie_page)
{
vsie_page->scb_s.icptcode = 0;
@@ -737,6 +756,8 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
int rc;
+ handle_last_fault(vcpu, vsie_page);
+
if (need_resched())
schedule();
if (test_cpu_flag(CIF_MCCK_PENDING))
@@ -928,6 +949,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
vsie_page = page_to_virt(page);
memset(&vsie_page->scb_s, 0, sizeof(struct kvm_s390_sie_block));
release_gmap_shadow(vsie_page);
+ vsie_page->fault_addr = 0;
vsie_page->scb_s.ihcpu = 0xffffU;
return vsie_page;
}
--
2.5.5
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