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charset="utf-8" No functional change intended. Signed-off-by: Demi Marie Obenour --- Changes since v2: - Keep MTRR_NUM_TYPES and adjust commit message accordingly --- xen/arch/x86/hvm/mtrr.c | 18 +++++++++--------- xen/arch/x86/include/asm/mtrr.h | 2 -- xen/arch/x86/mm/shadow/multi.c | 2 +- 3 files changed, 10 insertions(+), 12 deletions(-) diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c index 093103f6c768cf64f880d1b20e1c14f5918c1250..05e978041d62fd0d559462de181= a04bef8a5bca9 100644 --- a/xen/arch/x86/hvm/mtrr.c +++ b/xen/arch/x86/hvm/mtrr.c @@ -38,7 +38,7 @@ static const uint8_t pat_entry_2_pte_flags[8] =3D { =20 /* Effective mm type lookup table, according to MTRR and PAT. */ static const uint8_t mm_type_tbl[MTRR_NUM_TYPES][X86_NUM_MT] =3D { -#define RS MEMORY_NUM_TYPES +#define RS MTRR_NUM_TYPES #define UC X86_MT_UC #define WB X86_MT_WB #define WC X86_MT_WC @@ -66,9 +66,9 @@ static const uint8_t mm_type_tbl[MTRR_NUM_TYPES][X86_NUM_= MT] =3D { * Reverse lookup table, to find a pat type according to MTRR and effective * memory type. This table is dynamically generated. */ -static uint8_t __read_mostly mtrr_epat_tbl[MTRR_NUM_TYPES][MEMORY_NUM_TYPE= S] =3D - { [0 ... MTRR_NUM_TYPES-1] =3D - { [0 ... MEMORY_NUM_TYPES-1] =3D INVALID_MEM_TYPE } +static uint8_t __read_mostly mtrr_epat_tbl[MTRR_NUM_TYPES][MTRR_NUM_TYPES]= =3D + { [0 ... MTRR_NUM_TYPES - 1] =3D + { [0 ... MTRR_NUM_TYPES - 1] =3D INVALID_MEM_TYPE } }; =20 /* Lookup table for PAT entry of a given PAT value in host PAT. */ @@ -85,7 +85,7 @@ static int __init cf_check hvm_mtrr_pat_init(void) { unsigned int tmp =3D mm_type_tbl[i][j]; =20 - if ( tmp < MEMORY_NUM_TYPES ) + if ( tmp < MTRR_NUM_TYPES ) mtrr_epat_tbl[i][tmp] =3D j; } } @@ -317,11 +317,11 @@ static uint8_t effective_mm_type(struct mtrr_state *m, uint8_t gmtrr_mtype) { uint8_t mtrr_mtype, pat_value; - =20 + /* if get_pat_flags() gives a dedicated MTRR type, * just use it - */=20 - if ( gmtrr_mtype =3D=3D NO_HARDCODE_MEM_TYPE ) + */ + if ( gmtrr_mtype =3D=3D MTRR_NUM_TYPES ) mtrr_mtype =3D mtrr_get_type(m, gpa, 0); else mtrr_mtype =3D gmtrr_mtype; @@ -346,7 +346,7 @@ uint32_t get_pat_flags(struct vcpu *v, /* 1. Get the effective memory type of guest physical address, * with the pair of guest MTRR and PAT */ - guest_eff_mm_type =3D effective_mm_type(g, pat, gpaddr,=20 + guest_eff_mm_type =3D effective_mm_type(g, pat, gpaddr, gl1e_flags, gmtrr_mtype); /* 2. Get the memory type of host physical address, with MTRR */ shadow_mtrr_type =3D mtrr_get_type(&mtrr_state, spaddr, 0); diff --git a/xen/arch/x86/include/asm/mtrr.h b/xen/arch/x86/include/asm/mtr= r.h index e4f6ca6048334b2094a1836cc2f298453641232f..4b7f840a965954cc4b59698327a= 37e47026893a4 100644 --- a/xen/arch/x86/include/asm/mtrr.h +++ b/xen/arch/x86/include/asm/mtrr.h @@ -4,8 +4,6 @@ #include =20 #define MTRR_NUM_TYPES X86_MT_UCM -#define MEMORY_NUM_TYPES MTRR_NUM_TYPES -#define NO_HARDCODE_MEM_TYPE MTRR_NUM_TYPES =20 #define NORMAL_CACHE_MODE 0 #define NO_FILL_CACHE_MODE 2 diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c index f5f7ff021bd9e057c5b6f6329de7acb5ef05d58f..1faf9940db6b0afefc5977c00c0= 0fb6a39cd27d2 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -578,7 +578,7 @@ _sh_propagate(struct vcpu *v, gflags, gfn_to_paddr(target_gfn), mfn_to_maddr(target_mfn), - NO_HARDCODE_MEM_TYPE); + MTRR_NUM_TYPES); } } =20 --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab From nobody Wed May 1 10:32:13 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZM-MESSAGEID: 1673129280394100001 Setting cacheability flags that are not ones specified by Xen is a bug in the guest. By default, return -EINVAL if a guests attempts to do this. The invalid-cacheability=3D Xen command-line flag allows the administrator to allow such attempts or to produce Suggested-by: Andrew Cooper Signed-off-by: Demi Marie Obenour --- Changes since v6: - Make invalid-cacheability=3D a subflag of pv=3D. - Move check for invalid cacheability to get_page_from_l1e(). Changes since v5: - Make parameters static and __ro_after_init. - Replace boolean parameter allow_invalid_cacheability with string parameter invalid-cacheability. - Move parameter definitions to near where they are used. - Add documentation. Changes since v4: - Remove pointless BUILD_BUG_ON(). - Add comment explaining why an exception is being injected. Changes since v3: - Add Andrew Cooper=E2=80=99s Suggested-by --- docs/misc/xen-command-line.pandoc | 11 ++++++ xen/arch/x86/include/asm/pv/domain.h | 7 ++++ xen/arch/x86/mm.c | 53 +++++++++++++++++++++++++++- xen/arch/x86/pv/domain.c | 18 ++++++++-- 4 files changed, 85 insertions(+), 4 deletions(-) diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line= .pandoc index 424b12cfb27d6ade2ec63eacb8afe5df82465451..0230a7bc17cbd4362a42ea64cea= 695f31f5e0f86 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -1417,6 +1417,17 @@ detection of systems known to misbehave upon accesse= s to that port. ### idle_latency_factor (x86) > `=3D ` =20 +### invalid-cacheability (x86) +> `=3D allow | deny | trap` + +> Default: `deny` in release builds, otherwise `trap` + +Specify what happens when a PV guest tries to use one of the reserved entr= ies in +the PAT. `deny` causes the attempt to be rejected with -EINVAL, `allow` a= llows +the attempt, and `trap` causes a general protection fault to be raised. +Currently, the reserved entries are marked as uncacheable in Xen's PAT, bu= t this +will change if new memory types are added, so guests must not rely on it. + ### ioapic_ack (x86) > `=3D old | new` =20 diff --git a/xen/arch/x86/include/asm/pv/domain.h b/xen/arch/x86/include/as= m/pv/domain.h index 924508bbb4f0c199b3cd2306d9d8f0bd0ef399f9..1c9ce259ab4ee23ea5d057f5dfa= 964effb169032 100644 --- a/xen/arch/x86/include/asm/pv/domain.h +++ b/xen/arch/x86/include/asm/pv/domain.h @@ -71,6 +71,13 @@ void pv_vcpu_destroy(struct vcpu *v); int pv_vcpu_initialise(struct vcpu *v); void pv_domain_destroy(struct domain *d); int pv_domain_initialise(struct domain *d); +extern __ro_after_init uint8_t invalid_cacheability; + +enum { + INVALID_CACHEABILITY_ALLOW, + INVALID_CACHEABILITY_DENY, + INVALID_CACHEABILITY_TRAP, +}; =20 /* * Bits which a PV guest can toggle in its view of cr4. Some are loaded i= nto diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 3558ca215b02a517d55d75329d645ae5905424e4..a8f137925cba1846b97aee9321d= f6427f4dd1a94 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -879,6 +879,30 @@ get_page_from_l1e( return -EINVAL; } =20 + if ( invalid_cacheability !=3D INVALID_CACHEABILITY_ALLOW ) + { + switch ( l1e.l1 & PAGE_CACHE_ATTRS ) + { + case _PAGE_WB: + case _PAGE_UC: + case _PAGE_UCM: + case _PAGE_WC: + case _PAGE_WT: + case _PAGE_WP: + break; + default: + /* + * If we get here, a PV guest tried to use one of the + * reserved values in Xen's PAT. This indicates a bug + * in the guest. If requested by the user, inject #GP + * to cause the guest to log a stack trace. + */ + if ( invalid_cacheability =3D=3D INVALID_CACHEABILITY_TRAP ) + pv_inject_hw_exception(TRAP_gp_fault, 0); + return -EINVAL; + } + } + valid =3D mfn_valid(_mfn(mfn)); =20 if ( !valid || @@ -1324,6 +1348,31 @@ static int put_page_from_l4e(l4_pgentry_t l4e, mfn_t= l4mfn, unsigned int flags) return put_pt_page(l4e_get_page(l4e), mfn_to_page(l4mfn), flags); } =20 +#ifdef NDEBUG +#define INVALID_CACHEABILITY_DEFAULT INVALID_CACHEABILITY_DENY +#else +#define INVALID_CACHEABILITY_DEFAULT INVALID_CACHEABILITY_TRAP +#endif + +__ro_after_init uint8_t invalid_cacheability =3D + INVALID_CACHEABILITY_DEFAULT; + +static int __init cf_check set_invalid_cacheability(const char *str) +{ + if (strcmp("allow", str) =3D=3D 0) + invalid_cacheability =3D INVALID_CACHEABILITY_ALLOW; + else if (strcmp("deny", str) =3D=3D 0) + invalid_cacheability =3D INVALID_CACHEABILITY_DENY; + else if (strcmp("trap", str) =3D=3D 0) + invalid_cacheability =3D INVALID_CACHEABILITY_TRAP; + else + return -EINVAL; + + return 0; +} + +custom_param("invalid-cacheability", set_invalid_cacheability); + static int promote_l1_table(struct page_info *page) { struct domain *d =3D page_get_owner(page); @@ -1343,7 +1392,9 @@ static int promote_l1_table(struct page_info *page) } else { - switch ( ret =3D get_page_from_l1e(pl1e[i], d, d) ) + l1_pgentry_t l1e =3D pl1e[i]; + + switch ( ret =3D get_page_from_l1e(l1e, d, d) ) { default: goto fail; diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c index f94f28c8e271549acb449ef2e129b928751f765d..40b424351fd99fe1fb0a5faa5b2= 0bf4070bb1d4a 100644 --- a/xen/arch/x86/pv/domain.c +++ b/xen/arch/x86/pv/domain.c @@ -28,9 +28,21 @@ static int __init cf_check parse_pv(const char *s) do { ss =3D strchr(s, ','); if ( !ss ) - ss =3D strchr(s, '\0'); - - if ( (val =3D parse_boolean("32", s, ss)) >=3D 0 ) + ss +=3D strlen(s); + if ( !strncmp("invalid-cacheability=3D", s, + sizeof("invalid-cacheability=3D") - 1) ) + { + const char *p =3D s + (sizeof("invalid-cacheability=3D") - 1); + if (ss - p =3D=3D 5 && !memcmp(p, "allow", 5)) + invalid_cacheability =3D INVALID_CACHEABILITY_ALLOW; + else if (ss - p =3D=3D 4 && !memcmp(p, "deny", 4)) + invalid_cacheability =3D INVALID_CACHEABILITY_DENY; + else if (ss - p =3D=3D 4 && !memcmp(p, "trap", 4)) + invalid_cacheability =3D INVALID_CACHEABILITY_TRAP; + else + rc =3D -EINVAL; + } + else if ( (val =3D parse_boolean("32", s, ss)) >=3D 0 ) { #ifdef CONFIG_PV32 opt_pv32 =3D val; --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab From nobody Wed May 1 10:32:13 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1673129278640594.1882764911423; 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charset="utf-8" It may be desirable to change Xen's PAT for various reasons. This requires changes to several _PAGE_* macros as well. Add static assertions to check that XEN_MSR_PAT is consistent with the _PAGE_* macros, and that _PAGE_WB is 0 as required by Linux. Signed-off-by: Demi Marie Obenour --- Changes since v6: - Remove overly-specific comment. - Remove double blank line. - Check that unused entries are distinct from higher entries that are used. - Have PTE_FLAGS_TO_CACHEATTR validate its argument. - Do not check if an unsigned number is negative. - Expand comment explaining why _PAGE_WB must be zero. Changes since v5: - Remove unhelpful comment. - Move a BUILD_BUG_ON. - Use fewer hardcoded constants in PTE_FLAGS_TO_CACHEATTR. - Fix coding style. Changes since v4: - Add lots of comments explaining what the various BUILD_BUG_ON()s mean. Changes since v3: - Refactor some macros - Avoid including a string literal in BUILD_BUG_ON Additional checks on PAT values Signed-off-by: Demi Marie Obenour --- xen/arch/x86/include/asm/page.h | 2 + xen/arch/x86/mm.c | 96 +++++++++++++++++++++++++++++++++ 2 files changed, 98 insertions(+) diff --git a/xen/arch/x86/include/asm/page.h b/xen/arch/x86/include/asm/pag= e.h index b585235d064a567082582c8e92a4e8283fd949ca..c7d77ab2901aa5bdb03a719af81= 0c6f8d8ba9d4e 100644 --- a/xen/arch/x86/include/asm/page.h +++ b/xen/arch/x86/include/asm/page.h @@ -338,6 +338,8 @@ void efi_update_l4_pgtable(unsigned int l4idx, l4_pgent= ry_t); #define _PAGE_UC ( _PAGE_PCD | _PAGE_PWT) #define _PAGE_WC (_PAGE_PAT ) #define _PAGE_WP (_PAGE_PAT | _PAGE_PWT) +#define _PAGE_RSVD_1 (_PAGE_PAT | _PAGE_PCD ) +#define _PAGE_RSVD_2 (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT) =20 /* * Debug option: Ensure that granted mappings are not implicitly unmapped. diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index a8f137925cba1846b97aee9321df6427f4dd1a94..d69e9bea6c30bc782ab4c331f42= 502f6e61a028a 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -890,6 +890,8 @@ get_page_from_l1e( case _PAGE_WT: case _PAGE_WP: break; + case _PAGE_RSVD_1: + case _PAGE_RSVD_2: default: /* * If we get here, a PV guest tried to use one of the @@ -6412,6 +6414,100 @@ static void __init __maybe_unused build_assertions(= void) * using different PATs will not work. */ BUILD_BUG_ON(XEN_MSR_PAT !=3D 0x050100070406ULL); + + /* + * _PAGE_WB must be zero. Linux PV guests assume that _PAGE_WB will be + * zero, and indeed Linux has a BUILD_BUG_ON validating that their ver= sion + * of _PAGE_WB *is* zero. Furthermore, since _PAGE_WB is zero, it is = quite + * likely to be omitted from various parts of Xen, and indeed L1 PTE + * validation code checks that ((l1f & PAGE_CACHE_ATTRs) =3D=3D 0), not + * ((l1f & PAGE_CACHE_ATTRs) =3D=3D _PAGE_WB). + */ + BUILD_BUG_ON(_PAGE_WB); + + /* _PAGE_RSVD_1 must be less than _PAGE_RSVD_2 */ + BUILD_BUG_ON(_PAGE_RSVD_1 >=3D _PAGE_RSVD_2); + +#define PAT_ENTRY(v) = \ + (BUILD_BUG_ON_ZERO(((v) < 0) || ((v) > 7)) + = \ + (0xFF & (XEN_MSR_PAT >> (8 * (v))))) + + /* Validate at compile-time that v is a valid value for a PAT entry */ +#define CHECK_PAT_ENTRY_VALUE(v) = \ + BUILD_BUG_ON((v) > X86_NUM_MT || (v) =3D=3D X86_MT_RSVD_2 || = \ + (v) =3D=3D X86_MT_RSVD_3) + + /* Validate at compile-time that PAT entry v is valid */ +#define CHECK_PAT_ENTRY(v) CHECK_PAT_ENTRY_VALUE(PAT_ENTRY(v)) + + /* + * If one of these trips, the corresponding entry in XEN_MSR_PAT is in= valid. + * This would cause Xen to crash (with #GP) at startup. + */ + CHECK_PAT_ENTRY(0); + CHECK_PAT_ENTRY(1); + CHECK_PAT_ENTRY(2); + CHECK_PAT_ENTRY(3); + CHECK_PAT_ENTRY(4); + CHECK_PAT_ENTRY(5); + CHECK_PAT_ENTRY(6); + CHECK_PAT_ENTRY(7); + + /* Macro version of pte_flags_to_cacheattr(), for use in BUILD_BUG_ON(= )s */ +#define PTE_FLAGS_TO_CACHEATTR(pte_value) = \ + /* Check that the _PAGE_* macros only use bits from PAGE_CACHE_ATTRS *= / \ + (BUILD_BUG_ON_ZERO(((pte_value) & PAGE_CACHE_ATTRS) !=3D (pte_value)) = | \ + (((pte_value) & _PAGE_PAT) >> 5) | = \ + (((pte_value) & (_PAGE_PCD | _PAGE_PWT)) >> 3)) + + CHECK_PAT_ENTRY(PTE_FLAGS_TO_CACHEATTR(_PAGE_RSVD_1)); + CHECK_PAT_ENTRY(PTE_FLAGS_TO_CACHEATTR(_PAGE_RSVD_2)); +#define PAT_ENTRY_FROM_FLAGS(x) PAT_ENTRY(PTE_FLAGS_TO_CACHEATTR(x)) + + /* Validate at compile time that X does not duplicate a smaller PAT en= try */ +#define CHECK_DUPLICATE_ENTRY(x, y) = \ + BUILD_BUG_ON((x) >=3D (y) && = \ + (PAT_ENTRY_FROM_FLAGS(x) =3D=3D PAT_ENTRY_FROM_FLAGS(y))) + + /* Check that a PAT-related _PAGE_* macro is correct */ +#define CHECK_PAGE_VALUE(page_value) do { = \ + /* Check that the _PAGE_* macros only use bits from PAGE_CACHE_ATTRS *= / \ + BUILD_BUG_ON(((_PAGE_ ## page_value) & PAGE_CACHE_ATTRS) !=3D = \ + (_PAGE_ ## page_value)); = \ + /* Check that the _PAGE_* are consistent with XEN_MSR_PAT */ = \ + BUILD_BUG_ON(PAT_ENTRY(PTE_FLAGS_TO_CACHEATTR(_PAGE_ ## page_value)) != =3D \ + (X86_MT_ ## page_value)); = \ + case _PAGE_ ## page_value:; /* ensure no duplicate values */ = \ + /* = \ + * Check that the _PAGE_* entries do not duplicate a smaller reserved = \ + * entry. = \ + */ = \ + CHECK_DUPLICATE_ENTRY(_PAGE_ ## page_value, _PAGE_RSVD_1); = \ + CHECK_DUPLICATE_ENTRY(_PAGE_ ## page_value, _PAGE_RSVD_2); = \ + CHECK_PAT_ENTRY(PTE_FLAGS_TO_CACHEATTR(_PAGE_ ## page_value)); = \ +} while ( false ) + + /* + * If one of these trips, the corresponding _PAGE_* macro is inconsist= ent + * with XEN_MSR_PAT. This would cause Xen to use incorrect cacheabili= ty + * flags, with results that are unknown and possibly harmful. + */ + switch (0) { + CHECK_PAGE_VALUE(WT); + CHECK_PAGE_VALUE(WB); + CHECK_PAGE_VALUE(WC); + CHECK_PAGE_VALUE(UC); + CHECK_PAGE_VALUE(UCM); + CHECK_PAGE_VALUE(WP); + case _PAGE_RSVD_1: + case _PAGE_RSVD_2: + break; + } +#undef CHECK_PAT_ENTRY +#undef CHECK_PAT_ENTRY_VALUE +#undef CHECK_PAGE_VALUE +#undef PAGE_FLAGS_TO_CACHEATTR +#undef PAT_ENTRY } =20 /* --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab From nobody Wed May 1 10:32:13 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1673129279897950.4593432077719; 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charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZM-MESSAGEID: 1673129281959100007 Due to a hardware errata, Intel integrated GPUs are incompatible with Xen's PAT. Using Linux's PAT is a workaround for this flaw. Signed-off-by: Demi Marie Obenour --- xen/arch/x86/Kconfig | 33 ++++++++++++++++++++++++++++ xen/arch/x86/include/asm/page.h | 12 ++++++++++ xen/arch/x86/include/asm/processor.h | 15 +++++++++++++ xen/arch/x86/mm.c | 2 ++ 4 files changed, 62 insertions(+) diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig index 6a7825f4ba3c98e0496415123fde79ee62f771fa..18efccedfd08873cd169a54825b= 0ba4256a12942 100644 --- a/xen/arch/x86/Kconfig +++ b/xen/arch/x86/Kconfig @@ -227,6 +227,39 @@ config XEN_ALIGN_2M =20 endchoice =20 +config LINUX_PAT + bool "Use Linux's PAT instead of Xen's default" + help + Use Linux's Page Attribute Table instead of the default Xen value. + + The Page Attribute Table (PAT) maps three bits in the page table entry + to the actual cacheability used by the processor. Many Intel + integrated GPUs have errata (bugs) that cause CPU access to GPU memory + to ignore the topmost bit. When using Xen's default PAT, this results + in caches not being flushed and incorrect images being displayed. The + default PAT used by Linux does not cause this problem. + + If you say Y here, you will be able to use Intel integrated GPUs that + are attached to your Linux dom0 or other Linux PV guests. However, + you will not be able to use non-Linux OSs in dom0, and attaching a PCI + device to a non-Linux PV guest will result in unpredictable guest + behavior. If you say N here, you will be able to use a non-Linux + dom0, and will be able to attach PCI devices to non-Linux PV guests. + + Note that saving a PV guest with an assigned PCI device on a machine + with one PAT and restoring it on a machine with a different PAT won't + work: the resulting guest may boot and even appear to work, but caches + will not be flushed when needed, with unpredictable results. HVM + (including PVH and PVHVM) guests and guests without assigned PCI + devices do not care what PAT Xen uses, and migration (even live) + between hypervisors with different PATs will work fine. Guests using + PV Shim care about the PAT used by the PV Shim firmware, not the + host=E2=80=99s PAT. Also, non-default PAT values are incompatible with= the + (deprecated) qemu-traditional stubdomain. + + Say Y if you are building a hypervisor for a Linux distribution that + supports Intel iGPUs. Say N otherwise. + config X2APIC_PHYSICAL bool "x2APIC Physical Destination mode" help diff --git a/xen/arch/x86/include/asm/page.h b/xen/arch/x86/include/asm/pag= e.h index c7d77ab2901aa5bdb03a719af810c6f8d8ba9d4e..03839eb2b78517332663daad208= 9677d7000852c 100644 --- a/xen/arch/x86/include/asm/page.h +++ b/xen/arch/x86/include/asm/page.h @@ -331,6 +331,7 @@ void efi_update_l4_pgtable(unsigned int l4idx, l4_pgent= ry_t); =20 #define PAGE_CACHE_ATTRS (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT) =20 +#ifndef CONFIG_LINUX_PAT /* Memory types, encoded under Xen's choice of MSR_PAT. */ #define _PAGE_WB ( 0) #define _PAGE_WT ( _PAGE_PWT) @@ -340,6 +341,17 @@ void efi_update_l4_pgtable(unsigned int l4idx, l4_pgen= try_t); #define _PAGE_WP (_PAGE_PAT | _PAGE_PWT) #define _PAGE_RSVD_1 (_PAGE_PAT | _PAGE_PCD ) #define _PAGE_RSVD_2 (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT) +#else +/* Memory types, encoded under Linux's choice of MSR_PAT. */ +#define _PAGE_WB ( 0) +#define _PAGE_WC ( _PAGE_PWT) +#define _PAGE_UCM ( _PAGE_PCD ) +#define _PAGE_UC ( _PAGE_PCD | _PAGE_PWT) +#define _PAGE_RSVD_1 (_PAGE_PAT ) +#define _PAGE_WP (_PAGE_PAT | _PAGE_PWT) +#define _PAGE_RSVD_2 (_PAGE_PAT | _PAGE_PCD ) +#define _PAGE_WT (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT) +#endif =20 /* * Debug option: Ensure that granted mappings are not implicitly unmapped. diff --git a/xen/arch/x86/include/asm/processor.h b/xen/arch/x86/include/as= m/processor.h index 60b902060914584957db8afa5c7c1e6abdad4d13..413b59ab284990cca192fa1dc44= b437f58bd282f 100644 --- a/xen/arch/x86/include/asm/processor.h +++ b/xen/arch/x86/include/asm/processor.h @@ -92,6 +92,20 @@ X86_EFLAGS_NT|X86_EFLAGS_DF|X86_EFLAGS_IF| \ X86_EFLAGS_TF) =20 +#ifdef CONFIG_LINUX_PAT +/* + * Host IA32_CR_PAT value to cover all memory types. This is not the defa= ult + * MSR_PAT value, but is the same as the one used by Linux. + */ +#define XEN_MSR_PAT ((_AC(X86_MT_WB, ULL) << 0x00) | \ + (_AC(X86_MT_WC, ULL) << 0x08) | \ + (_AC(X86_MT_UCM, ULL) << 0x10) | \ + (_AC(X86_MT_UC, ULL) << 0x18) | \ + (_AC(X86_MT_WB, ULL) << 0x20) | \ + (_AC(X86_MT_WP, ULL) << 0x28) | \ + (_AC(X86_MT_UCM, ULL) << 0x30) | \ + (_AC(X86_MT_WT, ULL) << 0x38)) +#else /* * Host IA32_CR_PAT value to cover all memory types. This is not the defa= ult * MSR_PAT value, and is an ABI with PV guests. @@ -104,6 +118,7 @@ (_AC(X86_MT_WP, ULL) << 0x28) | \ (_AC(X86_MT_UC, ULL) << 0x30) | \ (_AC(X86_MT_UC, ULL) << 0x38)) +#endif =20 #ifndef __ASSEMBLY__ =20 diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index d69e9bea6c30bc782ab4c331f42502f6e61a028a..042c1875a02092a3f19c293003e= f12209d88a450 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -6407,6 +6407,7 @@ unsigned long get_upper_mfn_bound(void) =20 static void __init __maybe_unused build_assertions(void) { +#ifndef CONFIG_LINUX_PAT /* * If this trips, any guests that blindly rely on the public API in xe= n.h * (instead of reading the PAT from Xen, as Linux 3.19+ does) will be @@ -6414,6 +6415,7 @@ static void __init __maybe_unused build_assertions(vo= id) * using different PATs will not work. */ BUILD_BUG_ON(XEN_MSR_PAT !=3D 0x050100070406ULL); +#endif =20 /* * _PAGE_WB must be zero. Linux PV guests assume that _PAGE_WB will be --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab