From: Jan Beulich Date: Fri, 17 Jun 2016 14:51:22 +0000 (+0200) Subject: hvmloader: limit CPUs exposed to guests X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~912 X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=08754333892407f415045c05659783baeb8fc5d4;p=xen.git hvmloader: limit CPUs exposed to guests Various Linux versions allocate (partial) per-CPU data for all of them, as there is no indication in MADT whether they're hotpluggable. That's a little wasteful in terms of resource consumption especially for - guests with not overly much memory assigned, - 32-bit guests not having overly much address space available. Therefore limit what we put into MADT to the "maxvcpus" value, and make sure AML doesn't touch memory addresses corresponding to CPUs beyond that value (we can't reasonably make the respective processor objects disappear). Signed-off-by: Jan Beulich Reviewed-by: Boris Ostrovsky Acked-by: Andrew Cooper --- diff --git a/tools/firmware/hvmloader/acpi/build.c b/tools/firmware/hvmloader/acpi/build.c index 503648ce97..1f7103eb6e 100644 --- a/tools/firmware/hvmloader/acpi/build.c +++ b/tools/firmware/hvmloader/acpi/build.c @@ -48,6 +48,7 @@ struct acpi_info { uint8_t com2_present:1; /* 0[1] - System has COM2? */ uint8_t lpt1_present:1; /* 0[2] - System has LPT1? */ uint8_t hpet_present:1; /* 0[3] - System has HPET? */ + uint16_t nr_cpus; /* 2 - Number of CPUs */ uint32_t pci_min, pci_len; /* 4, 8 - PCI I/O hole boundaries */ uint32_t madt_csum_addr; /* 12 - Address of MADT checksum */ uint32_t madt_lapic0_addr; /* 16 - Address of first MADT LAPIC struct */ @@ -55,9 +56,6 @@ struct acpi_info { uint64_t pci_hi_min, pci_hi_len; /* 24, 32 - PCI I/O hole boundaries */ }; -/* Number of processor objects in the chosen DSDT. */ -static unsigned int nr_processor_objects; - static void set_checksum( void *table, uint32_t checksum_offset, uint32_t length) { @@ -89,7 +87,7 @@ static struct acpi_20_madt *construct_madt(struct acpi_info *info) sz = sizeof(struct acpi_20_madt); sz += sizeof(struct acpi_20_madt_intsrcovr) * 16; sz += sizeof(struct acpi_20_madt_ioapic); - sz += sizeof(struct acpi_20_madt_lapic) * nr_processor_objects; + sz += sizeof(struct acpi_20_madt_lapic) * hvm_info->nr_vcpus; madt = mem_alloc(sz, 16); if (!madt) return NULL; @@ -142,8 +140,9 @@ static struct acpi_20_madt *construct_madt(struct acpi_info *info) io_apic->ioapic_addr = IOAPIC_BASE_ADDRESS; lapic = (struct acpi_20_madt_lapic *)(io_apic + 1); + info->nr_cpus = hvm_info->nr_vcpus; info->madt_lapic0_addr = (uint32_t)lapic; - for ( i = 0; i < nr_processor_objects; i++ ) + for ( i = 0; i < hvm_info->nr_vcpus; i++ ) { memset(lapic, 0, sizeof(*lapic)); lapic->type = ACPI_PROCESSOR_LOCAL_APIC; @@ -151,8 +150,7 @@ static struct acpi_20_madt *construct_madt(struct acpi_info *info) /* Processor ID must match processor-object IDs in the DSDT. */ lapic->acpi_processor_id = i; lapic->apic_id = LAPIC_ID(i); - lapic->flags = ((i < hvm_info->nr_vcpus) && - test_bit(i, hvm_info->vcpu_online) + lapic->flags = (test_bit(i, hvm_info->vcpu_online) ? ACPI_LOCAL_APIC_ENABLED : 0); lapic++; } @@ -534,14 +532,12 @@ void acpi_build_tables(struct acpi_config *config, unsigned int physical) dsdt = mem_alloc(config->dsdt_15cpu_len, 16); if (!dsdt) goto oom; memcpy(dsdt, config->dsdt_15cpu, config->dsdt_15cpu_len); - nr_processor_objects = 15; } else { dsdt = mem_alloc(config->dsdt_anycpu_len, 16); if (!dsdt) goto oom; memcpy(dsdt, config->dsdt_anycpu, config->dsdt_anycpu_len); - nr_processor_objects = HVM_MAX_VCPUS; } /* diff --git a/tools/firmware/hvmloader/acpi/dsdt.asl b/tools/firmware/hvmloader/acpi/dsdt.asl index e266dc2fcd..bd65823697 100644 --- a/tools/firmware/hvmloader/acpi/dsdt.asl +++ b/tools/firmware/hvmloader/acpi/dsdt.asl @@ -50,7 +50,8 @@ DefinitionBlock ("DSDT.aml", "DSDT", 2, "Xen", "HVM", 0) UAR2, 1, LTP1, 1, HPET, 1, - Offset(4), + Offset(2), + NCPU, 16, PMIN, 32, PLEN, 32, MSUA, 32, /* MADT checksum address */ diff --git a/tools/firmware/hvmloader/acpi/mk_dsdt.c b/tools/firmware/hvmloader/acpi/mk_dsdt.c index b567b38063..b2ade89674 100644 --- a/tools/firmware/hvmloader/acpi/mk_dsdt.c +++ b/tools/firmware/hvmloader/acpi/mk_dsdt.c @@ -150,6 +150,14 @@ int main(int argc, char **argv) indent(); printf("MSU, 8\n"); pop_block(); + /* Processor object helpers. */ + push_block("Method", "PMAT, 2"); + push_block("If", "LLess(Arg0, NCPU)"); + stmt("Return", "ToBuffer(Arg1)"); + pop_block(); + stmt("Return", "Buffer() {0, 8, 0xff, 0xff, 0, 0, 0, 0}"); + pop_block(); + /* Define processor objects and control methods. */ for ( cpu = 0; cpu < max_cpus; cpu++) { @@ -171,17 +179,22 @@ int main(int argc, char **argv) pop_block(); push_block("Method", "_MAT, 0"); - stmt("Return", "ToBuffer(MAT)"); + if ( cpu ) + stmt("Return", "PMAT (%d, MAT)", cpu); + else + stmt("Return", "ToBuffer(MAT)"); pop_block(); push_block("Method", "_STA"); + if ( cpu ) + push_block("If", "LLess(%d, \\_SB.NCPU)", cpu); push_block("If", "FLG"); stmt("Return", "0xF"); pop_block(); - push_block("Else", NULL); + if ( cpu ) + pop_block(); stmt("Return", "0x0"); pop_block(); - pop_block(); push_block("Method", "_EJ0, 1, NotSerialized"); stmt("Sleep", "0xC8");