QEMU-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Alistair Francis <alistair23@gmail.com>
To: Palmer Dabbelt <palmer@sifive.com>
Cc: "open list:RISC-V" <qemu-riscv@nongnu.org>,
	Anup Patel <Anup.Patel@wdc.com>,
	Alistair Francis <Alistair.Francis@wdc.com>,
	"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
	Atish Patra <Atish.Patra@wdc.com>
Subject: Re: [PATCH v1 04/28] target/riscv: Fix CSR perm checking for HS mode
Date: Wed, 16 Oct 2019 13:56:04 -0700
Message-ID: <CAKmqyKMf1bPSpM7RP1ULmOK7sKcUFA5Rbb_TkD7f0vTtu5fa1Q@mail.gmail.com> (raw)
In-Reply-To: <mhng-afa69c9b-17b7-4043-b204-512c92cf618a@palmer-si-x1e>

On Tue, Sep 10, 2019 at 7:48 AM Palmer Dabbelt <palmer@sifive.com> wrote:
>
> On Fri, 23 Aug 2019 16:38:00 PDT (-0700), Alistair Francis wrote:
> > Update the CSR permission checking to work correctly when we are in
> > HS-mode.
> >
> > Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> > ---
> >  target/riscv/csr.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> > index f767ad24be..471f23a1d0 100644
> > --- a/target/riscv/csr.c
> > +++ b/target/riscv/csr.c
> > @@ -799,9 +799,15 @@ int riscv_csrrw(CPURISCVState *env, int csrno, target_ulong *ret_value,
> >
> >      /* check privileges and return -1 if check fails */
> >  #if !defined(CONFIG_USER_ONLY)
> > -    int csr_priv = get_field(csrno, 0x300);
> > +    int csr_priv = env->priv;
>
> This isn't really "csr_priv" (ie, the priv needed to access the CSR) any more,
> it's really the effective priv of the machine.  Leaving the variable with the
> same name makes this hard to read, but I think it is correct.

I changed the name to effective_priv.

>
> >      int read_only = get_field(csrno, 0xC00) == 3;
> > -    if ((write_mask && read_only) || (env->priv < csr_priv)) {
> > +
> > +    if (riscv_has_ext(env, RVH) && !riscv_cpu_virt_enabled(env)) {
> > +        /* Plus 1 as we are in HS mode */
>
> The comment is useless, it doesn't say why we increment it.  Also, I don't
> think this is correct: doesn't it allow U mode to access S CSRs when H is
> present and V is disabled?

Yes, you are correct. I have changed it to check that we are in S mode.

>
> Something like
>
>     riscv_effective_priv(CPURISCVState *env)
>     {
>         if (riscv_has_ext(env, RVH) && env->priv == PRIV_S && !riscv_cpu_virt_enabled(env)) {
>             return PRIV_HS;

I don't like this as there is no PRIV_HS. It seems like a bad idea to
start using a reserved privilege level, if it is ever used we will
then be stuck updating this. I also don't think this is used anywhere
else. I have just fixed up the if statement and comment.

Alistair

>         }
>
>         return env->priv;
>     }
>
> would probably be used in a handful of places, and would be a drop in for
> env->priv here.
>
> > +        csr_priv++;
> > +    }
> > +
> > +    if ((write_mask && read_only) || (csr_priv < get_field(csrno, 0x300))) {
> >          return -1;
> >      }
> >  #endif


  reply index

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-23 23:37 [Qemu-devel] [PATCH v1 00/28] Add RISC-V Hypervisor Extension v0.4 Alistair Francis
2019-08-23 23:37 ` [Qemu-devel] [PATCH v1 01/28] target/riscv: Add the Hypervisor extension Alistair Francis
2019-08-27 15:26   ` Chih-Min Chao
2019-09-10 13:43   ` Palmer Dabbelt
2019-08-23 23:37 ` [Qemu-devel] [PATCH v1 02/28] target/riscv: Add the virtulisation mode Alistair Francis
2019-08-27 15:44   ` [Qemu-devel] [Qemu-riscv] " Chih-Min Chao
2019-08-28  0:08     ` Alistair Francis
2019-09-10 13:44   ` [Qemu-devel] " Palmer Dabbelt
2019-09-16 15:57     ` Alistair Francis
2019-08-23 23:37 ` [Qemu-devel] [PATCH v1 03/28] target/riscv: Add the force HS exception mode Alistair Francis
2019-08-27 15:46   ` Chih-Min Chao
2019-09-10 14:48   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 04/28] target/riscv: Fix CSR perm checking for HS mode Alistair Francis
2019-09-10 14:48   ` Palmer Dabbelt
2019-10-16 20:56     ` Alistair Francis [this message]
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 05/28] target/riscv: Add the Hypervisor CSRs to CPUState Alistair Francis
2019-08-27 15:50   ` [Qemu-devel] [Qemu-riscv] " Chih-Min Chao
2019-09-10 14:48   ` [Qemu-devel] " Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 06/28] target/riscv: Print priv and virt in disas log Alistair Francis
2019-09-10 14:48   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 07/28] target/riscv: Dump Hypervisor registers if enabled Alistair Francis
2019-09-10 14:48   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 08/28] target/riscv: Add Hypervisor CSR access functions Alistair Francis
2019-09-10 14:48   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 09/28] target/riscv: Add Hypervisor virtual CSRs accesses Alistair Francis
2019-09-10 14:48   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 10/28] target/riscv: Convert mie and mstatus to pointers Alistair Francis
2019-09-11  8:24   ` Palmer Dabbelt
2019-09-11 14:54     ` [Qemu-devel] [Qemu-riscv] " Jonathan Behrens
2019-09-17 23:33       ` Alistair Francis
2019-09-18  1:59         ` Jonathan Behrens
2019-09-18 23:47           ` Alistair Francis
2019-09-19 14:50             ` Richard Henderson
2019-09-19 16:58               ` Jonathan Behrens
2019-10-25 20:28                 ` Alistair Francis
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 11/28] target/riscv: Add background register swapping function Alistair Francis
2019-09-11 14:17   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 12/28] target/riscv: Add support for virtual interrupt setting Alistair Francis
2019-09-14 20:30   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 13/28] target/ricsv: Flush the TLB on virtulisation mode changes Alistair Francis
2019-09-14 20:30   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 14/28] target/riscv: Generate illegal instruction on WFI when V=1 Alistair Francis
2019-09-14 20:30   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 15/28] riscv: plic: Always set sip.SEIP bit for HS Alistair Francis
2019-09-14 20:32   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 16/28] target/riscv: Add hypvervisor trap support Alistair Francis
2019-09-20 14:01   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 17/28] target/riscv: Add Hypervisor trap return support Alistair Francis
2019-10-01 18:33   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 18/28] target/riscv: Add hfence instructions Alistair Francis
2019-10-01 18:34   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 19/28] target/riscv: Disable guest FP support based on virtual status Alistair Francis
2019-10-01 18:34   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 20/28] target/riscv: Mark both sstatus and vsstatus as dirty Alistair Francis
2019-10-01 18:34   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 21/28] target/riscv: Respect MPRV and SPRV for floating point ops Alistair Francis
2019-10-02 23:52   ` Palmer Dabbelt
2019-10-16 21:01     ` Alistair Francis
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 22/28] target/riscv: Allow specifying MMU stage Alistair Francis
2019-10-03 15:53   ` Palmer Dabbelt
2019-10-07 18:05     ` Alistair Francis
2019-10-16 19:02       ` Palmer Dabbelt
2019-10-16 21:25         ` Alistair Francis
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 23/28] target/riscv: Allow specifying number of MMU stages Alistair Francis
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 24/28] target/riscv: Implement second stage MMU Alistair Francis
2019-10-07 16:15   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 25/28] target/riscv: Call the second stage MMU in virtualisation mode Alistair Francis
2019-10-08 17:54   ` Palmer Dabbelt
2019-08-23 23:38 ` [Qemu-devel] [PATCH v1 26/28] target/riscv: Add support for the 32-bit MSTATUSH CSR Alistair Francis
2019-10-08 18:36   ` Palmer Dabbelt
2019-08-23 23:39 ` [Qemu-devel] [PATCH v1 27/28] target/riscv: Add the MSTATUS_MPV_ISSET helper macro Alistair Francis
2019-10-08 18:36   ` Palmer Dabbelt
2019-10-16 21:14     ` Alistair Francis
2019-08-23 23:39 ` [Qemu-devel] [PATCH v1 28/28] target/riscv: Allow enabling the Hypervisor extension Alistair Francis
2019-10-08 18:53   ` Palmer Dabbelt

Reply instructions:

You may reply publically 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=CAKmqyKMf1bPSpM7RP1ULmOK7sKcUFA5Rbb_TkD7f0vTtu5fa1Q@mail.gmail.com \
    --to=alistair23@gmail.com \
    --cc="qemu-devel@nongnu.org \
    --cc=Alistair.Francis@wdc.com \
    --cc=Anup.Patel@wdc.com \
    --cc=Atish.Patra@wdc.com \
    --cc=palmer@sifive.com \
    --cc=qemu-riscv@nongnu.org \
    /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

QEMU-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/qemu-devel/0 qemu-devel/git/0.git
	git clone --mirror https://lore.kernel.org/qemu-devel/1 qemu-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 qemu-devel qemu-devel/ https://lore.kernel.org/qemu-devel \
		qemu-devel@nongnu.org
	public-inbox-index qemu-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.nongnu.qemu-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git