lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 18 Oct 2017 16:34:04 +0200 From: Auger Eric <eric.auger@...hat.com> To: Christoffer Dall <cdall@...aro.org> Cc: eric.auger.pro@...il.com, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, marc.zyngier@....com, peter.maydell@...aro.org, andre.przywara@....com, wanghaibin.wang@...wei.com, wu.wubin@...wei.com, drjones@...hat.com, wei@...hat.com Subject: Re: [PATCH v4 06/11] KVM: arm/arm64: vgic-its: Check GITS_CBASER validity before processing commands Hi Christoffer, On 18/10/2017 00:10, Christoffer Dall wrote: > On Tue, Oct 17, 2017 at 09:10:04AM +0200, Eric Auger wrote: >> At the moment vgic_its_process_commands() does not >> check the CBASER is valid before processing any command. >> Let's fix that. >> >> Also rename cbaser local variable into cbaser_pa to avoid >> any confusion with the full register. >> >> Signed-off-by: Eric Auger <eric.auger@...hat.com> >> --- >> virt/kvm/arm/vgic/vgic-its.c | 13 ++++++++----- >> 1 file changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >> index 3b539d4..e18f1e4 100644 >> --- a/virt/kvm/arm/vgic/vgic-its.c >> +++ b/virt/kvm/arm/vgic/vgic-its.c >> @@ -1301,17 +1301,20 @@ static void vgic_mmio_write_its_cbaser(struct kvm *kvm, struct vgic_its *its, >> /* Must be called with the cmd_lock held. */ >> static void vgic_its_process_commands(struct kvm *kvm, struct vgic_its *its) >> { >> - gpa_t cbaser; >> + gpa_t cbaser_pa; >> u64 cmd_buf[4]; >> >> - /* Commands are only processed when the ITS is enabled. */ >> - if (!its->enabled) >> + /* >> + * Commands are only processed when the ITS is enabled and >> + * CBASER is valid >> + */ >> + if (!its->enabled || (!(its->cbaser & GITS_CBASER_VALID))) > > Is it valid to clear the CBASER valid bit after having enabled the ITS? > If not, I think you should check changes to CBASER and then this > shouldn't be necessary. Yes you're right. the spec says: When GITS_CTLR.Enable == 1 or GITS_CTLR.Quiescent == 0, writing this register (CBASER) is UNPREDICTABLE . Given we already check its->enabled in vgic_mmio_write_its_cbaser, I think it is safe to remove this patch. Thanks Eric > > > >> return; >> >> - cbaser = CBASER_ADDRESS(its->cbaser); >> + cbaser_pa = CBASER_ADDRESS(its->cbaser); >> >> while (its->cwriter != its->creadr) { >> - int ret = kvm_read_guest(kvm, cbaser + its->creadr, >> + int ret = kvm_read_guest(kvm, cbaser_pa + its->creadr, >> cmd_buf, ITS_CMD_SIZE); >> /* >> * If kvm_read_guest() fails, this could be due to the guest >> -- >> 2.5.5 >> > > Otherwise, this looks fine. > > Thanks, > -Christoffer >
Powered by blists - more mailing lists