Hi Andrew,
On 09.12.25 20:07, Andrew Cooper wrote:
Prior to commit 02e78311cdc6 ("x86/domctl: Make XEN_DOMCTL_set_address_size
singleshot") (Xen 4.9, 2016), it was possible for domains to switch to being
compat, and back again. Since then however, becoming compat is a singleton
action that can't be undone.
From the context it's clear to see the is_pv_32bit_domain() check is
redundant, and from the singleton nature being the only place setting
physaddr_bitsize, there's no need to check it for being 0.
No functional change.
Co-developed-by: Grygorii Strashko <[email protected]>
Signed-off-by: Andrew Cooper <[email protected]>
---
CC: Jan Beulich <[email protected]>
CC: Roger Pau Monné <[email protected]>
CC: Grygorii Strashko <[email protected]>
Split out of series to simplify things.
bloat-o-meter reports:
add/remove: 0/1 grow/shrink: 1/0 up/down: 25/-96 (-71)
Function old new delta
switch_compat 447 472 +25
domain_set_alloc_bitsize 96 - -96
which will mostly be the LFENCEs embedded in is_pv_32bit_domain().
Thank you for doing this.
Not sure if it's needed, any way.
Reviewed-by: Grygorii Strashko <[email protected]>
---
xen/arch/x86/include/asm/mm.h | 1 -
xen/arch/x86/pv/domain.c | 6 +++++-
xen/arch/x86/x86_64/mm.c | 13 -------------
3 files changed, 5 insertions(+), 15 deletions(-)
diff --git a/xen/arch/x86/include/asm/mm.h b/xen/arch/x86/include/asm/mm.h
index 17ca6666a34e..9438f5ea0119 100644
--- a/xen/arch/x86/include/asm/mm.h
+++ b/xen/arch/x86/include/asm/mm.h
@@ -619,7 +619,6 @@ void __iomem *ioremap_wc(paddr_t pa, size_t len);
extern int memory_add(unsigned long spfn, unsigned long epfn, unsigned int pxm);
-void domain_set_alloc_bitsize(struct domain *d);
unsigned int domain_clamp_alloc_bitsize(struct domain *d, unsigned int bits);
#define domain_clamp_alloc_bitsize(d, bits) domain_clamp_alloc_bitsize(d,
bits)
diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c
index 9c4785c187dd..11db6a6d8396 100644
--- a/xen/arch/x86/pv/domain.c
+++ b/xen/arch/x86/pv/domain.c
@@ -254,7 +254,11 @@ int switch_compat(struct domain *d)
goto undo_and_fail;
}
- domain_set_alloc_bitsize(d);
+ if ( MACH2PHYS_COMPAT_NR_ENTRIES(d) < max_page )
+ d->arch.physaddr_bitsize =
+ /* 2^n entries can be contained in guest's p2m mapping space */
+ fls(MACH2PHYS_COMPAT_NR_ENTRIES(d)) - 1 + PAGE_SHIFT;
+
recalculate_cpuid_policy(d);
d->arch.x87_fip_width = 4;
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index d4e6a9c0a2e0..42fd4fe4e9b5 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1119,19 +1119,6 @@ int handle_memadd_fault(unsigned long addr, struct
cpu_user_regs *regs)
return ret;
}
-void domain_set_alloc_bitsize(struct domain *d)
-{
- if ( !is_pv_32bit_domain(d) ||
- (MACH2PHYS_COMPAT_NR_ENTRIES(d) >= max_page) ||
- d->arch.physaddr_bitsize > 0 )
- return;
- d->arch.physaddr_bitsize =
- /* 2^n entries can be contained in guest's p2m mapping space */
- fls(MACH2PHYS_COMPAT_NR_ENTRIES(d)) - 1
- /* 2^n pages -> 2^(n+PAGE_SHIFT) bits */
- + PAGE_SHIFT;
-}
-
unsigned int domain_clamp_alloc_bitsize(struct domain *d, unsigned int bits)
{
if ( (d == NULL) || (d->arch.physaddr_bitsize == 0) )
--
Best regards,
-grygorii
