On 6/1/23 09:01, Nico Boehr wrote:
This is to prepare for running guests without MSO/MSL, which is
currently not possible.
This is a preparation patch for non-MSO/MSL guest support.
We already have code in sie64a to setup a guest primary ASCE before
entering SIE, so we can in theory switch to the page tables which
translate gpa to hpa.
The important information that's missing here is that SIE always uses
the prim space for guest to host translations.
But the host is running in primary space mode already, so changing the
primary ASCE before entering SIE will also affect the host's code and
data.
And that's why this is an issue.
For the time being we'll copy the primary ASCE into the home space ASCE.
No functional change is intended. But if a test intends to....
To make this switch useful, the host should run in a different address
space mode. Hence, set up and change to home address space mode before
installing the guest ASCE.
The home space ASCE is just copied over from the primary space ASCE, so
no functional change is intended, also for tests that want to use
MSO/MSL. If a test intends to use a different primary space ASCE, it can
now just set the guest.asce in the save_area.
Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
lib/s390x/asm/arch_def.h | 1 +
lib/s390x/sie.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 84f6996c4d8c..099289e7550e 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -90,6 +90,7 @@ struct cpu {
#define AS_HOME 3
#define PSW_MASK_DAT 0x0400000000000000UL
+#define PSW_MASK_HOME 0x0000C00000000000UL
#define PSW_MASK_IO 0x0200000000000000UL
#define PSW_MASK_EXT 0x0100000000000000UL
#define PSW_MASK_KEY 0x00F0000000000000UL
diff --git a/lib/s390x/sie.c b/lib/s390x/sie.c
index 9241b4b4a512..ffa8ec91a423 100644
--- a/lib/s390x/sie.c
+++ b/lib/s390x/sie.c
@@ -46,6 +46,8 @@ void sie_handle_validity(struct vm *vm)
void sie(struct vm *vm)
{
+ uint64_t old_cr13;
+
if (vm->sblk->sdf == 2)
memcpy(vm->sblk->pv_grregs, vm->save_area.guest.grs,
sizeof(vm->save_area.guest.grs));
@@ -53,6 +55,16 @@ void sie(struct vm *vm)
/* Reset icptcode so we don't trip over it below */
vm->sblk->icptcode = 0;
+ /* set up home address space to match primary space */
+ old_cr13 = stctg(13);
+ lctlg(13, stctg(1));
+
+ /* switch to home space so guest tables can be different from host */
+ psw_mask_set_bits(PSW_MASK_HOME);
+
+ /* also handle all interruptions in home space while in SIE */
+ irq_set_dat_mode(IRQ_DAT_ON, AS_HOME);
I'm wondering why this needs to be two calls when you clearly want to
have a convenience function that does a full space change.
We could introduce:
#define AS_REAL 4
static void mmu_set_addr_space(uint8_t space)
{
if (space < 4)
psw_mask_set_bits(space);
irq_set_dat_mode(space);
}
The "addr" in the function name is optional in my opinion.
@Claudio: What's your opinion?
+
while (vm->sblk->icptcode == 0) {
sie64a(vm->sblk, &vm->save_area);
sie_handle_validity(vm);
@@ -60,6 +72,12 @@ void sie(struct vm *vm)
vm->save_area.guest.grs[14] = vm->sblk->gg14;
vm->save_area.guest.grs[15] = vm->sblk->gg15;
+ irq_set_dat_mode(IRQ_DAT_ON, AS_PRIM);
+ psw_mask_clear_bits(PSW_MASK_HOME);
+
+ /* restore the old CR 13 */
+ lctlg(13, old_cr13);
+
if (vm->sblk->sdf == 2)
memcpy(vm->save_area.guest.grs, vm->sblk->pv_grregs,
sizeof(vm->save_area.guest.grs));
