On 13/09/16 14:00, Sergej Proskurin wrote:
Hi Julien,
Hello Sergej,
On 09/12/2016 10:47 AM, Julien Grall wrote:
Hello Sergej,
On 16/08/2016 23:16, Sergej Proskurin wrote:
Signed-off-by: Sergej Proskurin <prosku...@sec.in.tum.de>
---
Cc: Stefano Stabellini <sstabell...@kernel.org>
Cc: Julien Grall <julien.gr...@arm.com>
---
v3: Extended the function "altp2m_switch_domain_altp2m_by_id" so that if
the guest domain indirectly calles this function, the current
vcpu also
changes the altp2m view without performing an explicit context
switch.
Exchanged the check "altp2m_vttbr[idx] == INVALID_VTTBR" for
"altp2m_p2m[idx] == NULL" in "altp2m_switch_domain_altp2m_by_id".
---
xen/arch/arm/altp2m.c | 48
++++++++++++++++++++++++++++++++++++++++++++
xen/arch/arm/hvm.c | 2 +-
xen/include/asm-arm/altp2m.h | 4 ++++
3 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/altp2m.c b/xen/arch/arm/altp2m.c
index c14ab0b..ba345b9 100644
--- a/xen/arch/arm/altp2m.c
+++ b/xen/arch/arm/altp2m.c
@@ -32,6 +32,54 @@ struct p2m_domain *altp2m_get_altp2m(struct vcpu *v)
return v->domain->arch.altp2m_p2m[index];
}
+int altp2m_switch_domain_altp2m_by_id(struct domain *d, unsigned int
idx)
+{
+ struct vcpu *v;
+ int rc = -EINVAL;
+
+ if ( idx >= MAX_ALTP2M )
+ return rc;
+
+ domain_pause_except_self(d);
+
+ altp2m_lock(d);
+
+ if ( d->arch.altp2m_p2m[idx] != NULL )
+ {
+ for_each_vcpu( d, v )
+ if ( idx != altp2m_vcpu(v).p2midx )
Could you invert the condition to avoid another layer of nested if?
Did you mean checking for (idx == altp2m_vcpu(v).p2midx) and continue
the loop if the condition should be satisfied? If so, then sure thing :)
Correct.
+ {
+ atomic_dec(&altp2m_get_altp2m(v)->active_vcpus);
+ altp2m_vcpu(v).p2midx = idx;
+ atomic_inc(&altp2m_get_altp2m(v)->active_vcpus);
+
+ /*
+ * In case it is the guest domain, which indirectly
called this
+ * function, the current vcpu will not switch its
context
+ * within the function "p2m_restore_state". That is,
changing
+ * the altp2m_vcpu(v).p2midx will not lead to the
requested
+ * altp2m switch on that specific vcpu. To achieve
the desired
+ * behavior, we write to VTTBR_EL2 directly.
+ */
+ if ( v->domain == d && v == current )
v == current is enough.
Ok.
+ {
+ struct p2m_domain *ap2m = d->arch.altp2m_p2m[idx];
+
+ WRITE_SYSREG64(ap2m->vttbr, VTTBR_EL2);
+ isb();
I don't like the open-coding of VTTBR_EL2. I would much prefer a
separate helper to update it.
Sure, I can introduce an UPDATE_VTTBR macro (including the isb call) in
p2m.h and adjust the remaining writes to VTTBR_EL2 in p2m.c as well. I
hope, I understood you correctly.
Actually, I was concerned about having the following sequence spread:
VTTBR_EL2
isb
However, the isb is not necessary here because VTTBR_EL2 will not be
used until we return to the guest.
So I would be fine to keep WRITE_SYSREG64(ap2m->vttbr, VTTBR_EL2);
Regards,
--
Julien Grall
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