At the moment, enter_hypervisor_head() and leave_hypervisor_tail() are
used to deal with actions to be done before/after any guest request is
handled.
While they are meant to work in pair, the former is called for most of
the traps, including traps from the same exception level (i.e.
hypervisor) whilst the latter will only be called when returning to the
guest.
As pointed out, the enter_hypervisor_head() is not called from all the
traps, so this makes potentially difficult to extend it for the dealing
with same exception level.
Furthermore, some assembly only path will require to call
enter_hypervisor_tail(). So the function is now directly call by
assembly in for guest vector only. This means that the check whether we
are called in a guest trap can now be removed.
Take the opportunity to rename enter_hypervisor_tail() and
leave_hypervisor_tail() to something more meaningful and document them.
This should help everyone to understand the purpose of the two
functions.
Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
I haven't done the 32-bits part yet. I wanted to gather feedback before
looking in details how to integrate that with Arm32.
---
xen/arch/arm/arm64/entry.S | 4 ++-
xen/arch/arm/traps.c | 71
++++++++++++++++++++++------------------------
2 files changed, 37 insertions(+), 38 deletions(-)
diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S
index 40d9f3ec8c..9eafae516b 100644
--- a/xen/arch/arm/arm64/entry.S
+++ b/xen/arch/arm/arm64/entry.S
@@ -147,7 +147,7 @@
.if \hyp == 0 /* Guest mode */
- bl leave_hypervisor_tail /* Disables interrupts on return */
+ bl leave_hypervisor_to_guest /* Disables interrupts on return */
exit_guest \compat
@@ -175,6 +175,8 @@
SKIP_SYNCHRONIZE_SERROR_ENTRY_EXIT)
msr daifclr, \iflags
mov x0, sp
+ bl enter_hypervisor_from_guest
+ mov x0, sp
bl do_trap_\trap
1:
exit hyp=0, compat=\compat
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index a3b961bd06..20ba34ec91 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2006,47 +2006,46 @@ static inline bool needs_ssbd_flip(struct vcpu *v)
cpu_require_ssbd_mitigation();
}
-static void enter_hypervisor_head(struct cpu_user_regs *regs)
+/*
+ * Actions that needs to be done after exiting the guest and before any
+ * request from it is handled.
+ */
+void enter_hypervisor_from_guest(struct cpu_user_regs *regs)
{
- if ( guest_mode(regs) )
- {
- struct vcpu *v = current;
+ struct vcpu *v = current;
- /* If the guest has disabled the workaround, bring it back on. */
- if ( needs_ssbd_flip(v) )
- arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2_FID, 1, NULL);
+ /* If the guest has disabled the workaround, bring it back on. */
+ if ( needs_ssbd_flip(v) )
+ arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2_FID, 1, NULL);
- /*
- * If we pended a virtual abort, preserve it until it gets cleared.
- * See ARM ARM DDI 0487A.j D1.14.3 (Virtual Interrupts) for details,
- * but the crucial bit is "On taking a vSError interrupt, HCR_EL2.VSE
- * (alias of HCR.VA) is cleared to 0."
- */
- if ( v->arch.hcr_el2 & HCR_VA )
- v->arch.hcr_el2 = READ_SYSREG(HCR_EL2);
+ /*
+ * If we pended a virtual abort, preserve it until it gets cleared.
+ * See ARM ARM DDI 0487A.j D1.14.3 (Virtual Interrupts) for details,
+ * but the crucial bit is "On taking a vSError interrupt, HCR_EL2.VSE
+ * (alias of HCR.VA) is cleared to 0."
+ */
+ if ( v->arch.hcr_el2 & HCR_VA )
+ v->arch.hcr_el2 = READ_SYSREG(HCR_EL2);
#ifdef CONFIG_NEW_VGIC
- /*
- * We need to update the state of our emulated devices using level
- * triggered interrupts before syncing back the VGIC state.
- *
- * TODO: Investigate whether this is necessary to do on every
- * trap and how it can be optimised.
- */
- vtimer_update_irqs(v);
- vcpu_update_evtchn_irq(v);
+ /*
+ * We need to update the state of our emulated devices using level
+ * triggered interrupts before syncing back the VGIC state.
+ *
+ * TODO: Investigate whether this is necessary to do on every
+ * trap and how it can be optimised.
+ */
+ vtimer_update_irqs(v);
+ vcpu_update_evtchn_irq(v);
#endif
- vgic_sync_from_lrs(v);
- }
+ vgic_sync_from_lrs(v);
}
void do_trap_guest_sync(struct cpu_user_regs *regs)
{
const union hsr hsr = { .bits = regs->hsr };
- enter_hypervisor_head(regs);
-
switch ( hsr.ec )
{
case HSR_EC_WFI_WFE:
@@ -2180,8 +2179,6 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
{
const union hsr hsr = { .bits = regs->hsr };
- enter_hypervisor_head(regs);
-
switch ( hsr.ec )
{
#ifdef CONFIG_ARM_64
@@ -2218,27 +2215,21 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
void do_trap_hyp_serror(struct cpu_user_regs *regs)
{
- enter_hypervisor_head(regs);
-
__do_trap_serror(regs, VABORT_GEN_BY_GUEST(regs));
}
void do_trap_guest_serror(struct cpu_user_regs *regs)
{
- enter_hypervisor_head(regs);
-
__do_trap_serror(regs, true);
}
void do_trap_irq(struct cpu_user_regs *regs)
{
- enter_hypervisor_head(regs);
gic_interrupt(regs, 0);
}
void do_trap_fiq(struct cpu_user_regs *regs)
{
- enter_hypervisor_head(regs);
gic_interrupt(regs, 1);
}
