From: Paul Mackerras <paulus@ozlabs.org>
To: Claudio Carvalho <cclaudio@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>,
Michael Anderson <andmike@linux.ibm.com>,
Ram Pai <linuxram@us.ibm.com>,
kvm-ppc@vger.kernel.org, Bharata B Rao <bharata@linux.ibm.com>,
linuxppc-dev@ozlabs.org, Ryan Grimm <grimm@linux.ibm.com>,
Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>,
Guerney Hunt <gdhh@linux.ibm.com>,
Thiago Bauermann <bauerman@linux.ibm.com>
Subject: Re: [PATCH v6 7/7] powerpc/kvm: Use UV_RETURN ucall to return to ultravisor
Date: Fri, 23 Aug 2019 13:59:58 +1000 [thread overview]
Message-ID: <20190823035958.tqpdtck2pl3foq5i@oak.ozlabs.ibm.com> (raw)
In-Reply-To: <20190822034838.27876-8-cclaudio@linux.ibm.com>
On Thu, Aug 22, 2019 at 12:48:38AM -0300, Claudio Carvalho wrote:
> From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
>
> When an SVM makes an hypercall or incurs some other exception, the
> Ultravisor usually forwards (a.k.a. reflects) the exceptions to the
> Hypervisor. After processing the exception, Hypervisor uses the
> UV_RETURN ultracall to return control back to the SVM.
>
> The expected register state on entry to this ultracall is:
>
> * Non-volatile registers are restored to their original values.
> * If returning from an hypercall, register R0 contains the return value
> (unlike other ultracalls) and, registers R4 through R12 contain any
> output values of the hypercall.
> * R3 contains the ultracall number, i.e UV_RETURN.
> * If returning with a synthesized interrupt, R2 contains the
> synthesized interrupt number.
This isn't accurate: R2 contains the value that should end up in SRR1
when we are back in the secure guest. HSRR0 and HSRR1 contain the
instruction pointer and MSR that the guest should run with. They may
be different from the instruction pointer and MSR that the guest vCPU
last had, if the hypervisor has synthesized an interrupt for the
guest. The ultravisor needs to detect this case and respond
appropriately.
> Thanks to input from Paul Mackerras, Ram Pai and Mike Anderson.
>
> Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Apart from that comment on the patch description -
Acked-by: Paul Mackerras <paulus@ozlabs.org>
prev parent reply other threads:[~2019-08-23 4:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 3:48 [PATCH v6 0/7] kvmppc: Paravirtualize KVM to support ultravisor Claudio Carvalho
2019-08-22 3:48 ` [PATCH v6 1/7] Documentation/powerpc: Ultravisor API Claudio Carvalho
2019-09-02 3:06 ` Michael Ellerman
2019-08-22 3:48 ` [PATCH v6 2/7] powerpc/kernel: Add ucall_norets() ultravisor call handler Claudio Carvalho
2019-08-22 3:48 ` [PATCH v6 3/7] powerpc/powernv: Introduce FW_FEATURE_ULTRAVISOR Claudio Carvalho
2019-08-23 7:07 ` Michael Ellerman
2019-08-22 3:48 ` [PATCH v6 4/7] powerpc/mm: Use UV_WRITE_PATE ucall to register a PATE Claudio Carvalho
2019-08-22 3:48 ` [PATCH v6 5/7] powerpc/mm: Write to PTCR only if ultravisor disabled Claudio Carvalho
2019-08-22 3:48 ` [PATCH v6 6/7] powerpc/powernv: Access LDBAR " Claudio Carvalho
2019-08-22 3:48 ` [PATCH v6 7/7] powerpc/kvm: Use UV_RETURN ucall to return to ultravisor Claudio Carvalho
2019-08-23 3:59 ` Paul Mackerras [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190823035958.tqpdtck2pl3foq5i@oak.ozlabs.ibm.com \
--to=paulus@ozlabs.org \
--cc=andmike@linux.ibm.com \
--cc=bauerman@linux.ibm.com \
--cc=bharata@linux.ibm.com \
--cc=cclaudio@linux.ibm.com \
--cc=gdhh@linux.ibm.com \
--cc=grimm@linux.ibm.com \
--cc=kvm-ppc@vger.kernel.org \
--cc=linuxppc-dev@ozlabs.org \
--cc=linuxram@us.ibm.com \
--cc=maddy@linux.vnet.ibm.com \
--cc=sukadev@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).