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Date: Mon, 8 Mar 2021 16:18:10 +0100
From: Christian Borntraeger <borntraeger@...ibm.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>,
linux-kernel@...r.kernel.org
Cc: frankja@...ux.ibm.com, david@...hat.com, cohuck@...hat.com,
kvm@...r.kernel.org, linux-s390@...r.kernel.org,
stable@...r.kernel.org
Subject: 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@...r.kernel.org
> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
> Acked-by: Janosch Frank <frankja@...ux.ibm.com>
> Reviewed-by: David Hildenbrand <david@...hat.com>
looks sane.
Acked-by: Christian Borntraeger <borntraeger@...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;
> }
>
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