[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] IOMMU/x86: new command line option to suppress use of superpage mappings
commit 6fc03330cdee0286290c650eb0d6fa1fc7778e79 Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Mon Jul 25 15:34:55 2022 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Mon Jul 25 15:34:55 2022 +0200 IOMMU/x86: new command line option to suppress use of superpage mappings Before actually enabling their use, provide a means to suppress it in case of problems. Note that using the option can also affect the sharing of page tables in the VT-d / EPT combination: If EPT would use large page mappings but the option is in effect, page table sharing would be suppressed (to properly fulfill the admin request). Requested-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx> Reviewed-by: Paul Durrant <paul@xxxxxxx> --- docs/misc/xen-command-line.pandoc | 8 +++++++- xen/arch/x86/include/asm/iommu.h | 2 +- xen/drivers/passthrough/iommu.c | 2 ++ xen/drivers/passthrough/vtd/iommu.c | 6 ++++-- xen/drivers/passthrough/x86/iommu.c | 6 ++++++ 5 files changed, 20 insertions(+), 4 deletions(-) diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index 971f47a77e..21d632e83a 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -1405,7 +1405,7 @@ detection of systems known to misbehave upon accesses to that port. ### iommu = List of [ <bool>, verbose, debug, force, required, quarantine[=scratch-page], - sharept, intremap, intpost, crash-disable, + sharept, superpages, intremap, intpost, crash-disable, snoop, qinval, igfx, amd-iommu-perdev-intremap, dom0-{passthrough,strict} ] @@ -1481,6 +1481,12 @@ boolean (e.g. `iommu=no`) can override this and leave the IOMMUs disabled. This option is ignored on ARM, and the pagetables are always shared. +* The `superpages` boolean controls whether superpage mappings may be used + in IOMMU page tables. If using this option is necessary to fix an issue, + please report a bug. + + This option is only valid on x86. + * The `intremap` boolean controls the Interrupt Remapping sub-feature, and is active by default on compatible hardware. On x86 systems, the first generation of IOMMUs only supported DMA remapping, and Interrupt Remapping diff --git a/xen/arch/x86/include/asm/iommu.h b/xen/arch/x86/include/asm/iommu.h index a80dfb2d7f..4143723727 100644 --- a/xen/arch/x86/include/asm/iommu.h +++ b/xen/arch/x86/include/asm/iommu.h @@ -132,7 +132,7 @@ extern bool untrusted_msi; int pi_update_irte(const struct pi_desc *pi_desc, const struct pirq *pirq, const uint8_t gvec); -extern bool iommu_non_coherent; +extern bool iommu_non_coherent, iommu_superpages; static inline void iommu_sync_cache(const void *addr, unsigned int size) { diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c index 1eae9393b2..134cdb47e0 100644 --- a/xen/drivers/passthrough/iommu.c +++ b/xen/drivers/passthrough/iommu.c @@ -88,6 +88,8 @@ static int __init cf_check parse_iommu_param(const char *s) iommu_igfx = val; else if ( (val = parse_boolean("qinval", s, ss)) >= 0 ) iommu_qinval = val; + else if ( (val = parse_boolean("superpages", s, ss)) >= 0 ) + iommu_superpages = val; #endif else if ( (val = parse_boolean("verbose", s, ss)) >= 0 ) iommu_verbose = val; diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c index f1e91b3d18..99c28ce160 100644 --- a/xen/drivers/passthrough/vtd/iommu.c +++ b/xen/drivers/passthrough/vtd/iommu.c @@ -2213,8 +2213,10 @@ static bool __init vtd_ept_page_compatible(const struct vtd_iommu *iommu) if ( rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, ept_cap) != 0 ) return false; - return (ept_has_2mb(ept_cap) && opt_hap_2mb) <= cap_sps_2mb(vtd_cap) && - (ept_has_1gb(ept_cap) && opt_hap_1gb) <= cap_sps_1gb(vtd_cap); + return (ept_has_2mb(ept_cap) && opt_hap_2mb) <= + (cap_sps_2mb(vtd_cap) && iommu_superpages) && + (ept_has_1gb(ept_cap) && opt_hap_1gb) <= + (cap_sps_1gb(vtd_cap) && iommu_superpages); } static int cf_check intel_iommu_add_device(u8 devfn, struct pci_dev *pdev) diff --git a/xen/drivers/passthrough/x86/iommu.c b/xen/drivers/passthrough/x86/iommu.c index 8ac4044c08..b4d9da7cf8 100644 --- a/xen/drivers/passthrough/x86/iommu.c +++ b/xen/drivers/passthrough/x86/iommu.c @@ -31,6 +31,7 @@ const struct iommu_init_ops *__initdata iommu_init_ops; struct iommu_ops __ro_after_init iommu_ops; bool __read_mostly iommu_non_coherent; +bool __initdata iommu_superpages = true; enum iommu_intremap __read_mostly iommu_intremap = iommu_intremap_full; @@ -104,8 +105,13 @@ int __init iommu_hardware_setup(void) mask_IO_APIC_setup(ioapic_entries); } + if ( !iommu_superpages ) + iommu_ops.page_sizes &= PAGE_SIZE_4K; + rc = iommu_init_ops->setup(); + ASSERT(iommu_superpages || iommu_ops.page_sizes == PAGE_SIZE_4K); + if ( ioapic_entries ) { restore_IO_APIC_setup(ioapic_entries, rc); -- generated by git-patchbot for /home/xen/git/xen.git#master
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