Re: [PATCH v5 3/3] s390/kvm: VSIE: correctly handle MVPG when in VSIE

On 02.03.21 18:44, Claudio Imbrenda wrote:

Correctly handle the MVPG instruction when issued by a VSIE guest.

Fixes: a3508fbe9dc6d ("KVM: s390: vsie: initial support for nested virtualization") Cc: stable@vger.kernel.org Signed-off-by: Claudio Imbrenda imbrenda@linux.ibm.com Acked-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: David Hildenbrand david@redhat.com

looks sane.

Acked-by: Christian Borntraeger borntraeger@de.ibm.com

---

arch/s390/kvm/vsie.c | 98 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 93 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 78b604326016..48aab6290a77 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -417,11 +417,6 @@ static void unshadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) memcpy((void *)((u64)scb_o + 0xc0), (void *)((u64)scb_s + 0xc0), 0xf0 - 0xc0); break;

• case ICPT_PARTEXEC:

• /* MVPG only */
  

• memcpy((void *)((u64)scb_o + 0xc0),
  

•        (void *)((u64)scb_s + 0xc0), 0xd0 - 0xc0);
  

• break;
  

  }

  if (scb_s->ihcpu != 0xffffU)

@@ -983,6 +978,95 @@ static int handle_stfle(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) return 0; }

+/*

• • Get a register for a nested guest.
• • @vcpu the vcpu of the guest
• • @vsie_page the vsie_page for the nested guest
• • @reg the register number, the upper 4 bits are ignored.
• • returns: the value of the register.
• */

+static u64 vsie_get_register(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page, u8 reg) +{

• /* no need to validate the parameter and/or perform error handling */
• reg &= 0xf;
• switch (reg) {
• case 15:

• return vsie_page->scb_s.gg15;
  

• case 14:

• return vsie_page->scb_s.gg14;
  

• default:

• return vcpu->run->s.regs.gprs[reg];
  

• }

+}

+static int vsie_handle_mvpg(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) +{

• struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
• unsigned long pei_dest, pei_src, src, dest, mask;
• u64 *pei_block = &vsie_page->scb_o->mcic;
• int edat, rc_dest, rc_src;
• union ctlreg0 cr0;
• cr0.val = vcpu->arch.sie_block->gcr[0];
• edat = cr0.edat && test_kvm_facility(vcpu->kvm, 8);
• mask = _kvm_s390_logical_to_effective(&scb_s->gpsw, PAGE_MASK);
• dest = vsie_get_register(vcpu, vsie_page, scb_s->ipb >> 16) & mask;
• src = vsie_get_register(vcpu, vsie_page, scb_s->ipb >> 20) & mask;
• rc_dest = kvm_s390_shadow_fault(vcpu, vsie_page->gmap, dest, &pei_dest);
• rc_src = kvm_s390_shadow_fault(vcpu, vsie_page->gmap, src, &pei_src);
• /*

• * Either everything went well, or something non-critical went wrong
  

• * e.g. because of a race. In either case, simply retry.
  

• */
  

• if (rc_dest == -EAGAIN || rc_src == -EAGAIN || (!rc_dest && !rc_src)) {

• retry_vsie_icpt(vsie_page);
  

• return -EAGAIN;
  

• }
• /* Something more serious went wrong, propagate the error */
• if (rc_dest < 0)

• return rc_dest;
  

• if (rc_src < 0)

• return rc_src;
  

• /* The only possible suppressing exception: just deliver it */
• if (rc_dest == PGM_TRANSLATION_SPEC || rc_src == PGM_TRANSLATION_SPEC) {

• clear_vsie_icpt(vsie_page);
  

• rc_dest = kvm_s390_inject_program_int(vcpu, PGM_TRANSLATION_SPEC);
  

• WARN_ON_ONCE(rc_dest);
  

• return 1;
  

• }
• /*

• * Forward the PEI intercept to the guest if it was a page fault, or
  

• * also for segment and region table faults if EDAT applies.
  

• */
  

• if (edat) {

• rc_dest = rc_dest == PGM_ASCE_TYPE ? rc_dest : 0;
  

• rc_src = rc_src == PGM_ASCE_TYPE ? rc_src : 0;
  

• } else {

• rc_dest = rc_dest != PGM_PAGE_TRANSLATION ? rc_dest : 0;
  

• rc_src = rc_src != PGM_PAGE_TRANSLATION ? rc_src : 0;
  

• }
• if (!rc_dest && !rc_src) {

• pei_block[0] = pei_dest;
  

• pei_block[1] = pei_src;
  

• return 1;
  

• }
• retry_vsie_icpt(vsie_page);
• /*

• * The host has edat, and the guest does not, or it was an ASCE type
  

• * exception. The host needs to inject the appropriate DAT interrupts
  

• * into the guest.
  

• */
  

• if (rc_dest)

• return inject_fault(vcpu, rc_dest, dest, 1);
  

• return inject_fault(vcpu, rc_src, src, 0);

+}

• /*
  • Run the vsie on a shadow scb and a shadow gmap, without any further
  • sanity checks, handling SIE faults.

@@ -1071,6 +1155,10 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) if ((scb_s->ipa & 0xf000) != 0xf000) scb_s->ipa += 0x1000; break;

• case ICPT_PARTEXEC:

• if (scb_s->ipa == 0xb254)
  

• 	rc = vsie_handle_mvpg(vcpu, vsie_page);
  

• break;
  

  } return rc; }