On 14.02.20 19:05, David Hildenbrand wrote:
> On 07.02.20 12:39, Christian Borntraeger wrote:
>> From: Vasily Gorbik <gor@xxxxxxxxxxxxx>
>>
>> Add exceptions handlers performing transparent transition of non-secure
>> pages to secure (import) upon guest access and secure pages to
>> non-secure (export) upon hypervisor access.
>>
>> Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
>> [frankja@xxxxxxxxxxxxx: adding checks for failures]
>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
>> [imbrenda@xxxxxxxxxxxxx: adding a check for gmap fault]
>> Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
>> [borntraeger@xxxxxxxxxx: patch merging, splitting, fixing]
>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>> ---
>> arch/s390/kernel/pgm_check.S | 4 +-
>> arch/s390/mm/fault.c | 86 ++++++++++++++++++++++++++++++++++++
>> 2 files changed, 88 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/s390/kernel/pgm_check.S b/arch/s390/kernel/pgm_check.S
>> index 59dee9d3bebf..27ac4f324c70 100644
>> --- a/arch/s390/kernel/pgm_check.S
>> +++ b/arch/s390/kernel/pgm_check.S
>> @@ -78,8 +78,8 @@ PGM_CHECK(do_dat_exception) /* 39 */
>> PGM_CHECK(do_dat_exception) /* 3a */
>> PGM_CHECK(do_dat_exception) /* 3b */
>> PGM_CHECK_DEFAULT /* 3c */
>> -PGM_CHECK_DEFAULT /* 3d */
>> -PGM_CHECK_DEFAULT /* 3e */
>> +PGM_CHECK(do_secure_storage_access) /* 3d */
>> +PGM_CHECK(do_non_secure_storage_access) /* 3e */
>> PGM_CHECK_DEFAULT /* 3f */
>> PGM_CHECK_DEFAULT /* 40 */
>> PGM_CHECK_DEFAULT /* 41 */
>> diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
>> index 7b0bb475c166..fab4219fa0be 100644
>> --- a/arch/s390/mm/fault.c
>> +++ b/arch/s390/mm/fault.c
>> @@ -38,6 +38,7 @@
>> #include <asm/irq.h>
>> #include <asm/mmu_context.h>
>> #include <asm/facility.h>
>> +#include <asm/uv.h>
>> #include "../kernel/entry.h"
>>
>> #define __FAIL_ADDR_MASK -4096L
>> @@ -816,3 +817,88 @@ static int __init pfault_irq_init(void)
>> early_initcall(pfault_irq_init);
>>
>> #endif /* CONFIG_PFAULT */
>> +
>> +#if IS_ENABLED(CONFIG_KVM)
>> +void do_secure_storage_access(struct pt_regs *regs)
>> +{
>> + unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
>> + struct vm_area_struct *vma;
>> + struct mm_struct *mm;
>> + struct page *page;
>> + int rc;
>> +
>> + switch (get_fault_type(regs)) {
>> + case USER_FAULT:
>> + mm = current->mm;
>> + down_read(&mm->mmap_sem);
>> + vma = find_vma(mm, addr);
>> + if (!vma) {
>> + up_read(&mm->mmap_sem);
>> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
>> + break;
>> + }
>> + page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
>> + if (IS_ERR_OR_NULL(page)) {
>> + up_read(&mm->mmap_sem);
>> + break;
>> + }
>> + if (arch_make_page_accessible(page))
>> + send_sig(SIGSEGV, current, 0);
>> + put_page(page);
>> + up_read(&mm->mmap_sem);
>> + break;
>> + case KERNEL_FAULT:
>> + page = phys_to_page(addr);
>> + if (unlikely(!try_get_page(page)))
>> + break;
>> + rc = arch_make_page_accessible(page);
>> + put_page(page);
>> + if (rc)
>> + BUG();
>> + break;
>> + case VDSO_FAULT:
>> + /* fallthrough */
>> + case GMAP_FAULT:
>> + /* fallthrough */
>
> Could we ever get here from the SIE?
GMAP_FAULT is only set if we came from the sie critical section, so unless we have a bug no.
>
>> + default:
>> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
>> + WARN_ON_ONCE(1);
>> + }
>> +}
>> +NOKPROBE_SYMBOL(do_secure_storage_access);
>> +
>> +void do_non_secure_storage_access(struct pt_regs *regs)
>> +{
>> + unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
>> + struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
>> + struct uv_cb_cts uvcb = {
>> + .header.cmd = UVC_CMD_CONV_TO_SEC_STOR,
>> + .header.len = sizeof(uvcb),
>> + .guest_handle = gmap->guest_handle,
>> + .gaddr = gaddr,
>> + };
>> + int rc;
>> +
>> + if (get_fault_type(regs) != GMAP_FAULT) {
>> + do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
>> + WARN_ON_ONCE(1);
>> + return;
>> + }
>> +
>> + rc = uv_make_secure(gmap, gaddr, &uvcb);
>> + if (rc == -EINVAL && uvcb.header.rc != 0x104)
>> + send_sig(SIGSEGV, current, 0);
>
>
> Looks good to me, but I don't feel like being ready for an r-b. I'll
> have to let that sink in :)
>
> Assumed-is-okay-by: David Hildenbrand <david@xxxxxxxxxx>
>
>
