[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] x86/ept: limit calls to memory_type_changed()
commit c4e5cc2ccc5b8274d02f7855c4769839989bb349 Author: Roger Pau Monné <roger.pau@xxxxxxxxxx> AuthorDate: Thu Sep 29 14:44:10 2022 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Thu Sep 29 14:44:10 2022 +0200 x86/ept: limit calls to memory_type_changed() memory_type_changed() is currently only implemented for Intel EPT, and results in the invalidation of EMT attributes on all the entries in the EPT page tables. Such invalidation causes EPT_MISCONFIG vmexits when the guest tries to access any gfns for the first time, which results in the recalculation of the EMT for the accessed page. The vmexit and the recalculations are expensive, and as such should be avoided when possible. Remove the call to memory_type_changed() from XEN_DOMCTL_memory_mapping: there are no modifications of the iomem_caps ranges anymore that could alter the return of cache_flush_permitted() from that domctl. Encapsulate calls to memory_type_changed() resulting from changes to the domain iomem_caps or ioport_caps ranges in the helpers themselves (io{ports,mem}_{permit,deny}_access()), and add a note in epte_get_entry_emt() to remind that changes to the logic there likely need to be propagaed to the IO capabilities helpers. Note changes to the IO ports or memory ranges are not very common during guest runtime, but Citrix Hypervisor has an use case for them related to device passthrough. Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- xen/arch/x86/domctl.c | 4 ---- xen/arch/x86/include/asm/iocap.h | 34 ++++++++++++++++++++++++++++++---- xen/arch/x86/mm/p2m-ept.c | 4 ++++ xen/common/domctl.c | 4 ---- xen/include/xen/iocap.h | 39 +++++++++++++++++++++++++++++++++++---- 5 files changed, 69 insertions(+), 16 deletions(-) diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c index 020df615bd..e9bfbc57a7 100644 --- a/xen/arch/x86/domctl.c +++ b/xen/arch/x86/domctl.c @@ -232,8 +232,6 @@ long arch_do_domctl( ret = ioports_permit_access(d, fp, fp + np - 1); else ret = ioports_deny_access(d, fp, fp + np - 1); - if ( !ret ) - memory_type_changed(d); break; } @@ -666,8 +664,6 @@ long arch_do_domctl( "ioport_map: error %ld denying dom%d access to [%x,%x]\n", ret, d->domain_id, fmp, fmp + np - 1); } - if ( !ret ) - memory_type_changed(d); break; } diff --git a/xen/arch/x86/include/asm/iocap.h b/xen/arch/x86/include/asm/iocap.h index eee47228d4..53d87ae8a3 100644 --- a/xen/arch/x86/include/asm/iocap.h +++ b/xen/arch/x86/include/asm/iocap.h @@ -7,10 +7,11 @@ #ifndef __X86_IOCAP_H__ #define __X86_IOCAP_H__ -#define ioports_permit_access(d, s, e) \ - rangeset_add_range((d)->arch.ioport_caps, s, e) -#define ioports_deny_access(d, s, e) \ - rangeset_remove_range((d)->arch.ioport_caps, s, e) +#include <xen/sched.h> +#include <xen/rangeset.h> + +#include <asm/p2m.h> + #define ioports_access_permitted(d, s, e) \ rangeset_contains_range((d)->arch.ioport_caps, s, e) @@ -18,4 +19,29 @@ (!rangeset_is_empty((d)->iomem_caps) || \ !rangeset_is_empty((d)->arch.ioport_caps)) +static inline int ioports_permit_access(struct domain *d, unsigned long s, + unsigned long e) +{ + bool flush = cache_flush_permitted(d); + int ret = rangeset_add_range(d->arch.ioport_caps, s, e); + + if ( !ret && !is_iommu_enabled(d) && !flush ) + /* See comment in iomem_permit_access(). */ + memory_type_changed(d); + + return ret; +} + +static inline int ioports_deny_access(struct domain *d, unsigned long s, + unsigned long e) +{ + int ret = rangeset_remove_range(d->arch.ioport_caps, s, e); + + if ( !ret && !is_iommu_enabled(d) && !cache_flush_permitted(d) ) + /* See comment in iomem_deny_access(). */ + memory_type_changed(d); + + return ret; +} + #endif /* __X86_IOCAP_H__ */ diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c index b4919bad51..d61d66c20e 100644 --- a/xen/arch/x86/mm/p2m-ept.c +++ b/xen/arch/x86/mm/p2m-ept.c @@ -518,6 +518,10 @@ int epte_get_entry_emt(struct domain *d, gfn_t gfn, mfn_t mfn, return MTRR_TYPE_UNCACHABLE; } + /* + * Conditional must be kept in sync with the code in + * {iomem,ioports}_{permit,deny}_access(). + */ if ( type != p2m_mmio_direct && !is_iommu_enabled(d) && !cache_flush_permitted(d) ) { diff --git a/xen/common/domctl.c b/xen/common/domctl.c index 452266710a..69fb9abd34 100644 --- a/xen/common/domctl.c +++ b/xen/common/domctl.c @@ -716,8 +716,6 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl) ret = iomem_permit_access(d, mfn, mfn + nr_mfns - 1); else ret = iomem_deny_access(d, mfn, mfn + nr_mfns - 1); - if ( !ret ) - memory_type_changed(d); break; } @@ -778,8 +776,6 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl) "memory_map: error %ld removing dom%d access to [%lx,%lx]\n", ret, d->domain_id, mfn, mfn_end); } - /* Do this unconditionally to cover errors on above failure paths. */ - memory_type_changed(d); break; } diff --git a/xen/include/xen/iocap.h b/xen/include/xen/iocap.h index 1ca3858fc0..ffbc48b60f 100644 --- a/xen/include/xen/iocap.h +++ b/xen/include/xen/iocap.h @@ -7,13 +7,44 @@ #ifndef __XEN_IOCAP_H__ #define __XEN_IOCAP_H__ +#include <xen/sched.h> #include <xen/rangeset.h> #include <asm/iocap.h> +#include <asm/p2m.h> + +static inline int iomem_permit_access(struct domain *d, unsigned long s, + unsigned long e) +{ + bool flush = cache_flush_permitted(d); + int ret = rangeset_add_range(d->iomem_caps, s, e); + + if ( !ret && !is_iommu_enabled(d) && !flush ) + /* + * Only flush if the range(s) are empty before this addition and + * IOMMU is not enabled for the domain, otherwise it makes no + * difference for effective cache attribute calculation purposes. + */ + memory_type_changed(d); + + return ret; +} + +static inline int iomem_deny_access(struct domain *d, unsigned long s, + unsigned long e) +{ + int ret = rangeset_remove_range(d->iomem_caps, s, e); + + if ( !ret && !is_iommu_enabled(d) && !cache_flush_permitted(d) ) + /* + * Only flush if the range(s) are empty after this removal and + * IOMMU is not enabled for the domain, otherwise it makes no + * difference for effective cache attribute calculation purposes. + */ + memory_type_changed(d); + + return ret; +} -#define iomem_permit_access(d, s, e) \ - rangeset_add_range((d)->iomem_caps, s, e) -#define iomem_deny_access(d, s, e) \ - rangeset_remove_range((d)->iomem_caps, s, e) #define iomem_access_permitted(d, s, e) \ rangeset_contains_range((d)->iomem_caps, s, e) -- generated by git-patchbot for /home/xen/git/xen.git#staging
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