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Date: Mon, 19 Jul 2021 21:13:46 -0700 From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com> To: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Peter Zijlstra <peterz@...radead.org>, Andy Lutomirski <luto@...nel.org> Cc: Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>, Tony Luck <tony.luck@...el.com>, Dan Williams <dan.j.williams@...el.com>, Andi Kleen <ak@...ux.intel.com>, Kirill Shutemov <kirill.shutemov@...ux.intel.com>, Sean Christopherson <seanjc@...gle.com>, Kuppuswamy Sathyanarayanan <knsathya@...nel.org>, x86@...nel.org, linux-kernel@...r.kernel.org, Isaku Yamahata <isaku.yamahata@...el.com> Subject: [PATCH v3 7/7] x86/tdx: ioapic: Add shared bit for IOAPIC base address From: Isaku Yamahata <isaku.yamahata@...el.com> The kernel interacts with each bare-metal IOAPIC with a special MMIO page. When running under KVM, the guest's IOAPICs are emulated by KVM. When running as a TDX guest, the guest needs to mark each IOAPIC mapping as "shared" with the host. This ensures that TDX private protections are not applied to the page, which allows the TDX host emulation to work. Earlier patches in this series modified ioremap() so that ioremap()-created mappings such as virtio will be marked as shared. However, the IOAPIC code does not use ioremap() and instead uses the fixmap mechanism. Introduce a special fixmap helper just for the IOAPIC code. Ensure that it marks IOAPIC pages as "shared". This replaces set_fixmap_nocache() with __set_fixmap() since __set_fixmap() allows custom 'prot' values. Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com> Reviewed-by: Andi Kleen <ak@...ux.intel.com> Reviewed-by: Tony Luck <tony.luck@...el.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com> --- arch/x86/kernel/apic/io_apic.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index d5c691a3208b..be967c73683e 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -49,6 +49,7 @@ #include <linux/slab.h> #include <linux/memblock.h> #include <linux/msi.h> +#include <linux/protected_guest.h> #include <asm/irqdomain.h> #include <asm/io.h> @@ -65,6 +66,7 @@ #include <asm/irq_remapping.h> #include <asm/hw_irq.h> #include <asm/apic.h> +#include <asm/tdx.h> #define for_each_ioapic(idx) \ for ((idx) = 0; (idx) < nr_ioapics; (idx)++) @@ -2675,6 +2677,18 @@ static struct resource * __init ioapic_setup_resources(void) return res; } +static void io_apic_set_fixmap_nocache(enum fixed_addresses idx, + phys_addr_t phys) +{ + pgprot_t flags = FIXMAP_PAGE_NOCACHE; + + /* Set TDX guest shared bit in pgprot flags */ + if (prot_guest_has(PR_GUEST_SHARED_MAPPING_INIT)) + flags = pgprot_protected_guest(flags); + + __set_fixmap(idx, phys, flags); +} + void __init io_apic_init_mappings(void) { unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0; @@ -2707,7 +2721,7 @@ void __init io_apic_init_mappings(void) __func__, PAGE_SIZE, PAGE_SIZE); ioapic_phys = __pa(ioapic_phys); } - set_fixmap_nocache(idx, ioapic_phys); + io_apic_set_fixmap_nocache(idx, ioapic_phys); apic_printk(APIC_VERBOSE, "mapped IOAPIC to %08lx (%08lx)\n", __fix_to_virt(idx) + (ioapic_phys & ~PAGE_MASK), ioapic_phys); @@ -2836,7 +2850,7 @@ int mp_register_ioapic(int id, u32 address, u32 gsi_base, ioapics[idx].mp_config.flags = MPC_APIC_USABLE; ioapics[idx].mp_config.apicaddr = address; - set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address); + io_apic_set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address); if (bad_ioapic_register(idx)) { clear_fixmap(FIX_IO_APIC_BASE_0 + idx); return -ENODEV; -- 2.25.1
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