From: Stefano Stabellini <sstabellini@kernel.org>
To: Oleksandr Tyshchenko <olekstysh@gmail.com>
Cc: xen-devel@lists.xenproject.org,
Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Julien Grall <julien.grall@arm.com>
Subject: Re: [PATCH V3 21/23] xen/arm: Add mapcache invalidation handling
Date: Wed, 9 Dec 2020 18:30:39 -0800 (PST) [thread overview]
Message-ID: <alpine.DEB.2.21.2012091822300.20986@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <1606732298-22107-22-git-send-email-olekstysh@gmail.com>
On Mon, 30 Nov 2020, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
>
> We need to send mapcache invalidation request to qemu/demu everytime
> the page gets removed from a guest.
>
> At the moment, the Arm code doesn't explicitely remove the existing
> mapping before inserting the new mapping. Instead, this is done
> implicitely by __p2m_set_entry().
>
> So we need to recognize a case when old entry is a RAM page *and*
> the new MFN is different in order to set the corresponding flag.
> The most suitable place to do this is p2m_free_entry(), there
> we can find the correct leaf type. The invalidation request
> will be sent in do_trap_hypercall() later on.
Why is it sent in do_trap_hypercall() ?
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> CC: Julien Grall <julien.grall@arm.com>
>
> ---
> Please note, this is a split/cleanup/hardening of Julien's PoC:
> "Add support for Guest IO forwarding to a device emulator"
>
> Changes V1 -> V2:
> - new patch, some changes were derived from (+ new explanation):
> xen/ioreq: Make x86's invalidate qemu mapcache handling common
> - put setting of the flag into __p2m_set_entry()
> - clarify the conditions when the flag should be set
> - use domain_has_ioreq_server()
> - update do_trap_hypercall() by adding local variable
>
> Changes V2 -> V3:
> - update patch description
> - move check to p2m_free_entry()
> - add a comment
> - use "curr" instead of "v" in do_trap_hypercall()
> ---
> ---
> xen/arch/arm/p2m.c | 24 ++++++++++++++++--------
> xen/arch/arm/traps.c | 13 ++++++++++---
> 2 files changed, 26 insertions(+), 11 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 5b8d494..9674f6f 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1,6 +1,7 @@
> #include <xen/cpu.h>
> #include <xen/domain_page.h>
> #include <xen/iocap.h>
> +#include <xen/ioreq.h>
> #include <xen/lib.h>
> #include <xen/sched.h>
> #include <xen/softirq.h>
> @@ -749,17 +750,24 @@ static void p2m_free_entry(struct p2m_domain *p2m,
> if ( !p2m_is_valid(entry) )
> return;
>
> - /* Nothing to do but updating the stats if the entry is a super-page. */
> - if ( p2m_is_superpage(entry, level) )
> + if ( p2m_is_superpage(entry, level) || (level == 3) )
> {
> - p2m->stats.mappings[level]--;
> - return;
> - }
> +#ifdef CONFIG_IOREQ_SERVER
> + /*
> + * If this gets called (non-recursively) then either the entry
> + * was replaced by an entry with a different base (valid case) or
> + * the shattering of a superpage was failed (error case).
> + * So, at worst, the spurious mapcache invalidation might be sent.
> + */
> + if ( domain_has_ioreq_server(p2m->domain) &&
> + (p2m->domain == current->domain) && p2m_is_ram(entry.p2m.type) )
> + p2m->domain->mapcache_invalidate = true;
Why the (p2m->domain == current->domain) check? Shouldn't we set
mapcache_invalidate to true anyway? What happens if p2m->domain !=
current->domain? We wouldn't want the domain to lose the
mapcache_invalidate notification.
> +#endif
>
> - if ( level == 3 )
> - {
> p2m->stats.mappings[level]--;
> - p2m_put_l3_page(entry);
> + /* Nothing to do if the entry is a super-page. */
> + if ( level == 3 )
> + p2m_put_l3_page(entry);
> return;
> }
>
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index b6077d2..151c626 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -1443,6 +1443,7 @@ static void do_trap_hypercall(struct cpu_user_regs *regs, register_t *nr,
> const union hsr hsr)
> {
> arm_hypercall_fn_t call = NULL;
> + struct vcpu *curr = current;
Is this just to save 3 characters?
> BUILD_BUG_ON(NR_hypercalls < ARRAY_SIZE(arm_hypercall_table) );
>
> @@ -1459,7 +1460,7 @@ static void do_trap_hypercall(struct cpu_user_regs *regs, register_t *nr,
> return;
> }
>
> - current->hcall_preempted = false;
> + curr->hcall_preempted = false;
>
> perfc_incra(hypercalls, *nr);
> call = arm_hypercall_table[*nr].fn;
> @@ -1472,7 +1473,7 @@ static void do_trap_hypercall(struct cpu_user_regs *regs, register_t *nr,
> HYPERCALL_RESULT_REG(regs) = call(HYPERCALL_ARGS(regs));
>
> #ifndef NDEBUG
> - if ( !current->hcall_preempted )
> + if ( !curr->hcall_preempted )
> {
> /* Deliberately corrupt parameter regs used by this hypercall. */
> switch ( arm_hypercall_table[*nr].nr_args ) {
> @@ -1489,8 +1490,14 @@ static void do_trap_hypercall(struct cpu_user_regs *regs, register_t *nr,
> #endif
>
> /* Ensure the hypercall trap instruction is re-executed. */
> - if ( current->hcall_preempted )
> + if ( curr->hcall_preempted )
> regs->pc -= 4; /* re-execute 'hvc #XEN_HYPERCALL_TAG' */
> +
> +#ifdef CONFIG_IOREQ_SERVER
> + if ( unlikely(curr->domain->mapcache_invalidate) &&
> + test_and_clear_bool(curr->domain->mapcache_invalidate) )
> + ioreq_signal_mapcache_invalidate();
Why not just:
if ( unlikely(test_and_clear_bool(curr->domain->mapcache_invalidate)) )
ioreq_signal_mapcache_invalidate();
next prev parent reply other threads:[~2020-12-10 2:30 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-30 10:31 Oleksandr Tyshchenko
2020-11-30 10:31 ` [PATCH V3 01/23] x86/ioreq: Prepare IOREQ feature for making it common Oleksandr Tyshchenko
2020-12-01 11:03 ` Alex Bennée
2020-12-01 18:53 ` Oleksandr
2020-12-01 19:36 ` Alex Bennée
2020-12-02 8:00 ` Jan Beulich
2020-12-02 11:19 ` Oleksandr
2020-12-07 11:13 ` Jan Beulich
2020-12-07 15:27 ` Oleksandr
2020-12-07 16:29 ` Jan Beulich
2020-12-07 17:21 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 02/23] x86/ioreq: Add IOREQ_STATUS_* #define-s and update code for moving Oleksandr Tyshchenko
2020-12-01 11:07 ` Alex Bennée
2020-12-07 11:19 ` Jan Beulich
2020-12-07 15:37 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 03/23] x86/ioreq: Provide out-of-line wrapper for the handle_mmio() Oleksandr Tyshchenko
2020-12-07 11:27 ` Jan Beulich
2020-12-07 15:39 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 04/23] xen/ioreq: Make x86's IOREQ feature common Oleksandr Tyshchenko
2020-12-07 11:41 ` Jan Beulich
2020-12-07 19:43 ` Oleksandr
2020-12-08 9:21 ` Jan Beulich
2020-12-08 13:56 ` Oleksandr
2020-12-08 15:02 ` Jan Beulich
2020-12-08 17:24 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 05/23] xen/ioreq: Make x86's hvm_ioreq_needs_completion() common Oleksandr Tyshchenko
2020-12-07 11:47 ` Jan Beulich
2020-11-30 10:31 ` [PATCH V3 06/23] xen/ioreq: Make x86's hvm_mmio_first(last)_byte() common Oleksandr Tyshchenko
2020-12-07 11:48 ` Jan Beulich
2020-11-30 10:31 ` [PATCH V3 07/23] xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common Oleksandr Tyshchenko
2020-12-07 11:54 ` Jan Beulich
2020-11-30 10:31 ` [PATCH V3 08/23] xen/ioreq: Move x86's ioreq_server to struct domain Oleksandr Tyshchenko
2020-12-07 12:04 ` Jan Beulich
2020-12-07 12:12 ` Paul Durrant
2020-12-07 19:52 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 09/23] xen/dm: Make x86's DM feature common Oleksandr Tyshchenko
2020-12-07 12:08 ` Jan Beulich
2020-12-07 20:23 ` Oleksandr
2020-12-08 9:30 ` Jan Beulich
2020-12-08 14:54 ` Oleksandr
2021-01-07 14:38 ` Oleksandr
2021-01-07 15:01 ` Jan Beulich
2021-01-07 16:49 ` Oleksandr
2021-01-12 22:23 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 10/23] xen/mm: Make x86's XENMEM_resource_ioreq_server handling common Oleksandr Tyshchenko
2020-12-07 11:35 ` Jan Beulich
2020-12-07 12:11 ` Jan Beulich
2020-12-07 21:06 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 11/23] xen/ioreq: Move x86's io_completion/io_req fields to struct vcpu Oleksandr Tyshchenko
2020-12-07 12:32 ` Jan Beulich
2020-12-07 20:59 ` Oleksandr
2020-12-08 7:52 ` Paul Durrant
2020-12-08 9:35 ` Jan Beulich
2020-12-08 18:21 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 12/23] xen/ioreq: Remove "hvm" prefixes from involved function names Oleksandr Tyshchenko
2020-12-07 12:45 ` Jan Beulich
2020-12-07 20:28 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 13/23] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() Oleksandr Tyshchenko
2020-12-09 21:32 ` Stefano Stabellini
2020-12-09 22:34 ` Oleksandr
2020-12-10 2:30 ` Stefano Stabellini
2020-11-30 10:31 ` [PATCH V3 14/23] arm/ioreq: Introduce arch specific bits for IOREQ/DM features Oleksandr Tyshchenko
2020-12-09 22:04 ` Stefano Stabellini
2020-12-09 22:49 ` Oleksandr
2020-12-10 2:30 ` Stefano Stabellini
2020-11-30 10:31 ` [PATCH V3 15/23] xen/arm: Stick around in leave_hypervisor_to_guest until I/O has completed Oleksandr Tyshchenko
2020-11-30 20:51 ` Volodymyr Babchuk
2020-12-01 12:46 ` Julien Grall
2020-12-09 23:18 ` Stefano Stabellini
2020-12-09 23:35 ` Stefano Stabellini
2020-12-09 23:47 ` Julien Grall
2020-12-10 2:30 ` Stefano Stabellini
2020-12-10 13:17 ` Julien Grall
2020-12-10 13:21 ` Oleksandr
2020-12-09 23:38 ` Julien Grall
2020-11-30 10:31 ` [PATCH V3 16/23] xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm Oleksandr Tyshchenko
2020-12-08 14:24 ` Jan Beulich
2020-12-08 16:41 ` Oleksandr
2020-12-09 23:49 ` Stefano Stabellini
2021-01-15 1:18 ` Stefano Stabellini
2020-11-30 10:31 ` [PATCH V3 17/23] xen/ioreq: Introduce domain_has_ioreq_server() Oleksandr Tyshchenko
2020-12-08 15:11 ` Jan Beulich
2020-12-08 15:33 ` Oleksandr
2020-12-08 16:56 ` Oleksandr
2020-12-08 19:43 ` Paul Durrant
2020-12-08 20:16 ` Oleksandr
2020-12-09 9:01 ` Paul Durrant
2020-12-09 18:58 ` Julien Grall
2020-12-09 21:05 ` Oleksandr
2020-12-09 20:36 ` Oleksandr
2020-12-10 8:38 ` Paul Durrant
2020-12-10 16:57 ` Oleksandr
2020-11-30 10:31 ` [PATCH V3 18/23] xen/dm: Introduce xendevicemodel_set_irq_level DM op Oleksandr Tyshchenko
2020-12-10 2:21 ` Stefano Stabellini
2020-12-10 12:58 ` Oleksandr
2020-12-10 13:38 ` Julien Grall
2020-11-30 10:31 ` [PATCH V3 19/23] xen/arm: io: Abstract sign-extension Oleksandr Tyshchenko
2020-11-30 21:03 ` Volodymyr Babchuk
2020-11-30 23:27 ` Oleksandr
2020-12-01 7:55 ` Jan Beulich
2020-12-01 10:30 ` Julien Grall
2020-12-01 10:42 ` Oleksandr
2020-12-01 12:13 ` Julien Grall
2020-12-01 12:24 ` Oleksandr
2020-12-01 12:28 ` Julien Grall
2020-12-01 10:49 ` Jan Beulich
2020-12-01 10:23 ` Julien Grall
2020-11-30 10:31 ` [PATCH V3 20/23] xen/ioreq: Make x86's send_invalidate_req() common Oleksandr Tyshchenko
2020-12-08 15:24 ` Jan Beulich
2020-12-08 16:49 ` Oleksandr
2020-12-09 8:21 ` Jan Beulich
2020-11-30 10:31 ` [PATCH V3 21/23] xen/arm: Add mapcache invalidation handling Oleksandr Tyshchenko
2020-12-10 2:30 ` Stefano Stabellini [this message]
2020-12-10 18:50 ` Julien Grall
2020-12-11 1:28 ` Stefano Stabellini
2020-12-11 11:21 ` Oleksandr
2020-12-11 19:07 ` Stefano Stabellini
2020-12-11 19:37 ` Julien Grall
2020-12-11 19:27 ` Julien Grall
2020-11-30 10:31 ` [PATCH V3 22/23] libxl: Introduce basic virtio-mmio support on Arm Oleksandr Tyshchenko
2020-11-30 10:31 ` [PATCH V3 23/23] [RFC] libxl: Add support for virtio-disk configuration Oleksandr Tyshchenko
2020-11-30 11:22 ` [PATCH V3 00/23] IOREQ feature (+ virtio-mmio) on Arm Oleksandr
2020-12-07 13:03 ` Wei Chen
2020-12-07 21:03 ` Oleksandr
2020-11-30 16:21 ` Alex Bennée
2020-11-30 22:22 ` [PATCH V3 00/23] IOREQ feature (+ virtio-mmio) on Arm Oleksandr
2020-12-29 15:32 ` Roger Pau Monné
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