* [PATCH v2] x86/shim: Simplify compat handling in write_start_info()
@ 2021-04-20 17:41 Andrew Cooper
2021-04-21 9:29 ` Jan Beulich
0 siblings, 1 reply; 2+ messages in thread
From: Andrew Cooper @ 2021-04-20 17:41 UTC (permalink / raw)
To: Xen-devel; +Cc: Andrew Cooper, Jan Beulich, Roger Pau Monné, Wei Liu
Factor out a compat boolean to remove the lfence overhead from multiple
is_pv_32bit_domain() calls.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Wei Liu <wl@xen.org>
v2:
* Reinstate the conditional for the start info pointer, in case Intel/AMD
can't be persuaded to adjust the architectural guarentees for upper bits in
compatibility mode transitions.
---
xen/arch/x86/pv/shim.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index d16c0048c0..4c6f442274 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -280,12 +280,12 @@ void __init pv_shim_setup_dom(struct domain *d, l4_pgentry_t *l4start,
static void write_start_info(struct domain *d)
{
struct cpu_user_regs *regs = guest_cpu_user_regs();
- start_info_t *si = map_domain_page(_mfn(is_pv_32bit_domain(d) ? regs->edx
- : regs->rdx));
+ bool compat = is_pv_32bit_domain(d);
+ start_info_t *si = map_domain_page(_mfn(compat ? regs->edx : regs->rdx));
uint64_t param;
snprintf(si->magic, sizeof(si->magic), "xen-3.0-x86_%s",
- is_pv_32bit_domain(d) ? "32p" : "64");
+ compat ? "32p" : "64");
si->nr_pages = domain_tot_pages(d);
si->shared_info = virt_to_maddr(d->shared_info);
si->flags = 0;
@@ -300,7 +300,7 @@ static void write_start_info(struct domain *d)
&si->console.domU.mfn) )
BUG();
- if ( is_pv_32bit_domain(d) )
+ if ( compat )
xlat_start_info(si, XLAT_start_info_console_domU);
unmap_domain_page(si);
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] x86/shim: Simplify compat handling in write_start_info()
2021-04-20 17:41 [PATCH v2] x86/shim: Simplify compat handling in write_start_info() Andrew Cooper
@ 2021-04-21 9:29 ` Jan Beulich
0 siblings, 0 replies; 2+ messages in thread
From: Jan Beulich @ 2021-04-21 9:29 UTC (permalink / raw)
To: Andrew Cooper; +Cc: Roger Pau Monné, Wei Liu, Xen-devel
On 20.04.2021 19:41, Andrew Cooper wrote:
> Factor out a compat boolean to remove the lfence overhead from multiple
> is_pv_32bit_domain() calls.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> ---
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Roger Pau Monné <roger.pau@citrix.com>
> CC: Wei Liu <wl@xen.org>
>
> v2:
> * Reinstate the conditional for the start info pointer, in case Intel/AMD
> can't be persuaded to adjust the architectural guarentees for upper bits in
> compatibility mode transitions.
As indicated before, with this adjustment
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Jan
^ permalink raw reply [flat|nested] 2+ messages in thread
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